CA1226487A - Cod farming system - Google Patents
Cod farming systemInfo
- Publication number
- CA1226487A CA1226487A CA000534905A CA534905A CA1226487A CA 1226487 A CA1226487 A CA 1226487A CA 000534905 A CA000534905 A CA 000534905A CA 534905 A CA534905 A CA 534905A CA 1226487 A CA1226487 A CA 1226487A
- Authority
- CA
- Canada
- Prior art keywords
- codfish
- confinement means
- temporary
- cod
- confinement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01K—ANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
- A01K61/00—Culture of aquatic animals
- A01K61/60—Floating cultivation devices, e.g. rafts or floating fish-farms
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/80—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in fisheries management
- Y02A40/81—Aquaculture, e.g. of fish
Abstract
Cod Farming Method Abstract of the Disclosure The present invention as disclosed comprises a method of aquaculture of codfish. First, live codfish are captured by a cod trap such as that which has been traditionally used by Newfoundland fishermen. The aquaculture method of the present invention comprises the following steps:
placing the live codfish captured by a cod trap as indicated above in temporary confinement means filled with new water, such as a sea water tank installed on a seagoing vessel;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4°C to 8°C; and preferably, from -1.5° to 4°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish in the temporary confinement means;
controlling light and controlling fish density in said temporary confinement means to maintain a suitable optimum level for each of these parameters;
transporting the captured live codfish to an area provided with a permanent confinement means such as a floating net pen placed in the open sea;
placing said live codfish from the temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish:
supplying the codfish placed in the permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting the codfish which have grown to a desirable size.
placing the live codfish captured by a cod trap as indicated above in temporary confinement means filled with new water, such as a sea water tank installed on a seagoing vessel;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4°C to 8°C; and preferably, from -1.5° to 4°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish in the temporary confinement means;
controlling light and controlling fish density in said temporary confinement means to maintain a suitable optimum level for each of these parameters;
transporting the captured live codfish to an area provided with a permanent confinement means such as a floating net pen placed in the open sea;
placing said live codfish from the temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish:
supplying the codfish placed in the permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting the codfish which have grown to a desirable size.
Description
By The present invention relates to a method of fish-farming, being particularly directed to the trapping and growing of cod in the sea, with simplified means and procedures.
There is known a method of fish farming disclosed in Canadian Patent 1,172,115 which makes use ox a phenomenon observed with salmon, that is base on the fact that such fish prefer to stay under a light blocking cover and can be trained to stay under cover; and this method Lo can obviate the need for a conventional cage or other enclosing constructions.
There is also known another method of aquiculture of fish disclosed in Canadian Patent 1,041,849 which comprises establishing an aqueous euphoric zone in an enclosed body of water containing phytoplankton in said body of water above an aqueous bottom zone with the provision of nutrients in the said euphoric zone sufficient to cause growth of phytoplankton, and disposing a filter-feeding aquatic non-air breathing species in the body of water which will feed upon said phytoplankton and upon which said carnivorous species will feed, introducing said carnivorous species into said body of water.
Also known is a method of raising and harvesting fish as disclosed in Canadian Patent 945,845 wherein the fish are directed to the food source by an artificially created current. This results in the fish eating more food thereby reaching the desired size and weight in a shorter period of time. Growth of the fish is further enhanced by providing mechanism for aerating the water to assure the availability of an adequate supply of oxygen.
The invention described in that patent also provides for harvesting apparatus particularly adapted for use with the feeding apparatus which includes a container for confining the fish when they gather at the food source and structure for removing the confined fish from the container.
Previously all marine aquiculture methods and means have been confine to so-called "luxury" or high priced" species such as salmon or trout. This is largely -~lZ26 ~37 because the cost of producing hatchery-raised fingerlings is considered too high for species such as cod, haddock, flounder, sole, turbot, etc. (the so-called "white fishes").
Consequently, a high-volume "white fish"
a~uaculture industry capable ox competiting directly with other sources of meat such as mass-produced chicken has not been developed. Some work, however, has been done to create a hatchery system capable of the mass production ox cod fingerlings at a reasonable price.
The present invention represents a significant advance over the prior art by providing an efficient and cheap method of growing and harvesting cod.
Summary of The Invention In one embodiment the present invention resides in a method of aquiculture of codfish comprising the steps of:
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4C to 8DC preferably -1.5C to 4C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
Jo ., .
lZZ6~87 n another embodiment the present invention resides in a method of aquiculture of codfish comprising the steps of:
placing live codfish captured by coy trap means into temporary confinement means filled with sea water;
controlling the temperature ox said sea water so that said temperature is maintained within the range from -3~4C to 8C:
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said cod is in said temporary confinement means;
controlling light, and controlling fish density, in said temporary confinement means to maintain suitable lo optimum levels, transporting said captured jive codfish to a area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
placing live capelin captured by capelin trap means or capelin seine means into temporary confinement means containing sea water;
controlling the temperature of the water so that said temperature is maintained within the range of 0C to 8C;
regulating dissolved oxygen in the waters to maintain suitable living conditions for the capelin during confinement of said capelin in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels:
transporting said captured live capelin to an area provided with a permanent capelin storage or confinement means;
placing said live capelin from said temporary capelin A confinement means into an area provided with a permanent I' ~.Z'26~137 capelin confinement means provided for storing, and/or rearing; and or harvesting ox said capelin;
placing said capelin fish from said capelin transporting means into said permanent confinement means for feeding said codfish; and harvesting members of said codfish which have grown to a desirable size.
In a further embodiment, the present invention resides in a method of a~uaculture of codfish comprising the steps of:
placing of live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water in the range from -3.4C to 8C by refrigeration means;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish, by oxygen tank means;
controlling light and controlling fish-density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
In accordance with certain aspects of the present invention codfish are normally captured by means of cod traps.
The cod, when caught, are normally located at the bottom of the trap in a 4C to 6C band of water and, therefore, normally have a body temperature of 4C to ~:~Z6'~87 6C. There may be some advantage in depressing their body temperature below this level when they are placed into the well-boat.
The reasons for this are natively simple The body temperature of cod, like all poikilothermous vertebrates, can adjust passively to that of the surrounding water, as long as the rate of change of body temperature is not too great and/or other stress factors are not present.
In addition, and most importantly, oxygen consumption by the cod, which is a primary consideration in optimizing transport densities in the well boat from the trap to the farm, is lowered with decreasing water temperature.
In the present invention the temporary confinement means are normally sea water tans installed on a seagoing vessel such as a ship or large. On other situations it may be desirable to install temporary confinement means on a land vehicle such as a truck for expeditious delivery, for example in the case of a peninsula where the land trip would be much shorter than the trip by sea.
The permanent confinement means comprises a fish rearing enclosure such as a floating net pen placed in the open sea, preferably in a protected location. In a preferred embodiment of the invention the food supply to feed the codfish comprises Chaplin fish, which may be separately reared in an enclosure and then transported to the cod rearing enclosure serving as the permanent confinement means for the codfish, for feeding said codfish as required.
The present invention will now be described in further detail, with reference to the accompanying drawings, wherein:
Fig. 1 shows a notified Newfoundland cod trap:
Fig. 2 shows a typical inshore summer water temperature profile off ~ewfoundland's east coast;
~ZZ~87 Figs. 3 shows a water temperature profile off the east coast of Newfoundland in August, depending on weather conditions:
it. 4 is a plan view of a fish farm system according to one embodiment of the present invention; and Fig. 5 is a side elevation of a fish farm system as shown in Fig. 4.
The invention will now be explained in some detail, with reference to what is shown in the drawings.
The first step of the invention comprises catching live codfish in a suitable water layer, generally having a predetermined temperature and intensity of light which is favorable to cod. The catching means for this method could be a cod trap as shown in Fig. 1 which is a cod trap in use in Newfoundland and Labrador.
This and much of the other technical information set out in this specification and drawings can be found in a publication entitled "Trap Cod", published by the Communication Division, Canada Department of Fisheries and Oceans, Newfoundland Region, PRO. Box 5667, St. John's, Newfoundland Arc 5Xl, to which the present applicant is indebted.
The cod trap is a very efficient fishing gear, and can be very successful when used under the appropriate conditions. However, the trap fishery in Newfoundland has traditionally been plagued by serious problems. For example, catches can vary widely from season to season.
Also the trap catches mostly small fish. Catches in one year may be excellent, with fishermen jetting more fish than they can handle; in another year they may have great difficulty even scraping a "saving voyage". Catches in different areas may also show great variations.
The nature of the cod trap itself is one of the reasons for these fluctuations in catch. It is a stationary gear set in a specific location near the shore and must wait for the fish to come to it. About all a lZ~64~37 fisherman can do to improve the situation is move the trap to a new berth or shift it to deeper or shallower water in an existing location.
Thus, there are several possible reasons why the cod trap fishery experiences frequent failures, even though there may be plenty of fishermen, boats and traps employed to ensure a successful season.
Codfish prefer to inhabit water with a temperature of about OKAY to 8C, preferably I to 4C or lo SAC, although very small cod will tolerate somewhat warmer or colder water. Generally speaking the larger the codfish the deeper the water it prefers to live in.
figure 2 of the attached drawings illustrates typical inshore/near-shore water temperature conditions in Newfoundland waters and indicates what size cod are most likely to be taken (and the gear most likely to be used) at various water depths.
Of the many factors which can directly affect cod trap catches, probably the most important are hydrographic conditions. The most important of these are generally water temperature, currents or tides, and sea conditions.
Off the east coast of Newfoundland during the winter, the temperature of all inshore waters is likely to be about -1C to -1.5C. As the spring and summer advance, ice melts or moves off, the air gets increasingly warmer and surface water temperature starts to rise.
There are six rather simple, 'average' situations for a year that started with a late, cold spring, making for a cold trap season. The six situations are: 1) cold June, light variable or light onshore winds; 2) late June, strong offshore winds; 3) late June, strong onshore winds;
4) cold July, light variable or light onshore winds; 5) late July, strong offshore winds; 6) late July, strong onshore winds.
A typical situation in the month of June in a warm year with moderate onshore winds prevailing would be Jo ~l2Z64~'7 as follows. There is a warm layer of water, unsuitable for cod, about eight fathoms deep. Beneath that is a suitable layer going down to about 15 fathoms, with colder water lying beneath that. This is similar to the situation for a cold July with light onshore winds but it is somewhat better. The cod will now be congregated in a narrow layer between roughly 8 and I fathoms down, in good average trap depth. These conditions can mean good fishing for most traps and they could prevail right up into August or even later.
A situation which we might find in August in a cold year with light to moderate onshore winds prevailing is similar to the situation for a cold July with heavy onshore winds. The warm surface layer of water is not pushed quite as deep, however; it is down to only about 10 fathoms. The suitable layer for cod extends from 10 fathoms to about 23 fathoms deep. This might cut the cod off from traps in the 12-fathom depth range, but it should mean good fishing for deeper traps, as on the Avalon Peninsula, say, where the traps are usually set in the 18 to 20 fathom range.
Figure 3 of the attached drawings shows a typical kind of late-season situation. It might be found in August on a warm year with heavy onshore winds prevailing:
or in September on a cold year with heavy onshore winds or in September on a warm year with light to moderate onshore winds. In any case, either the summer temperatures or the onshore winds, or a combination of both, has by August or September created a deep surface layer of warm water extending down to about 13 fathoms or more. By this time, the water layer suitable for cod has likewise been pushed downward to about 40 fathoms. This is the end of the season for most trap fishermen, as the cod are now too deep for all but the deepest traps. The capelin have gone and the cod tend to be widely dispersed over a large bottom area, feeding off crab, shrimp and So ISSUE
other bottom living creatures. These conditions generally make for successful line trawl and near-shore gill net fisheries. It should be noticed that the deep water layer suitable for cod found at about the l00 fathom depth is a very stable one, and the long line and gill net fisheries conducted in this water is seldom, if ever, affected by the sort of hydrographic conditions described above.
Obviously, there is an almost endless number of situations that can arise. And things can be further lo complicated by local shoreline and bottom conditions, as they affect wind direction, currents, wave action and so on.
Observant fishermen, however, will soon recognize general patterns in the conditions in their particular areas. Those with a good basic understanding of the effects of winds and temperatures on the waters in their area may be able to take advantage of changing conditions to shift trap locations, or change to other gears from time to time, and so improve their chances of increasing their season's landings.
One piece of equipment needed to take advantage of changes in hydrographic conditions is a reversing water thermometer. By using the thermometer, a fisherman can determine the temperature of the water at different depths and set his trap at whatever depth has a suitable temperature range for cod (or change to another type of gear such as the line trawl).
Besides hydrographic conditions there are many other factors, which can make for a bad year, or two or three in a row (or particularly good years too, for that matter), in a local area or along an entire coastline.
For instance, if the overall size of the stock being fished is down, then chances are that trap catches will be down (along with catches by other gears as well).
Or the overall size of the stock may be quite large, but the stock might contain low numbers of the small size of 3l22~;48~
cod that are normally caught in traps. The amount of capelin that come inshore to spawn can affect trap landings, so can the amount of capelin that stay offshore because they are too young to spawn. The amount of sunlight, the presence of 'dirty water' and the spawning time of the cod are other factors which can help make or break a trap fisherman's season.
A successful inshore fishery requires a good supply of cod offshore in the range of sizes normally caught in the traps. The size of the northern cod stock is currently estimated to be about 1,500,000 t (metric tones), which should provide good catches inshore.
Sometimes the spawning in a particular year is not successful because of adverse ocean condition and few cod are born of that year-class. (A year-class is the cod born in a particular year; cod born in 1980, for example, would form the 1980 year-class.) Year-class success or failure is vital to the trap fishery. When two year-classes in succession are failures, there is a shortage several years later of cod in the traps and inshore generally, since it is cod of four to six years old that form the major portion of trap catches.
The inshore cod trap fishery takes place during the inshore spawning migration of capelin, which at this time are the major source of food for inshore cod. A lack of capelin in a local area could discourage cod from staying there They could move to other areas or into deeper water to search for food. However, the presence of large quantities of capelin in an area does not automatically ensure a good trap fishery. Conception and Trinity Bay fishermen experienced a poor trap fishery in recent years despite the fact that there were plenty of capelin in the bays.
During prolonged periods of bright sunlight, larger cod tend to move close inshore only during the night. During the day, they will move off to deeper 226~37 water, out of cod trap depth, to escape the light. The much smaller cod can endure brighter light, however, and Turing periods ox bright sunlight, only these very small wish, tweaked size, wit} stay in the area of the cod traps. The effect of sunlight is most pronounce when the water is very clear and calm and the light goes deeper than usual, making it possible to see bottom where normally it cannot be seen.
It should be mentioned that the following are main factors influencing the size of fish caught in a cod trap: mesh size, relative numbers of large and small fish which come in contact with the trap, relative numbers of large and small fish in the population or stock of cod being fished and geographical location of fishing effort.
Mesh size is important in determining the size of the fish which will escape and the size of those that will remain in the trap. We refer to this process as the mesh selection or selectivity of the trap.
Because the fish are brought on board toward the back of the trap, it is mainly through the back panel, and the side panels joined to the back, that they try to get away. Generally speaking, therefore, it is possible to influence the size of cod held in a trap by varying the mesh size used at the back of the trap.
Compared to other gears used in the inshore fishery, the cod trap tends to catch the smallest fish, mainly because smaller fish tend to be closer to shore where most cod traps are set. However, there are variations from year to year in the relative amounts of small and larger fish caught. Water temperatures or distribution and abundance of food may bring more large cod within range of the traps in some years. In certain areas, such as around headlands, deep water may run close to shore, and in such places larger cod may come within range of traps; traps set in deep water tend to catch a larger run of fish. Traps set in the bottom of bays, ~26~
where little trapping was cone until recently, tone to catch smaller fish.
It a cod stock is in a healthy or stable condition, all age groups, older ages in particular, will probably be abundant . As a stork it f idea it is usually the older, larger fish that get caught first. Overfishing plus poor survival of young fish reduces the population of both old and young wish. As the stock rebuilds, small fish in the younger age groups are more numerous.
This process has occurred with the 'northern' cod stock. In the early 1960's, before heavy fishing pressure, this stock was made up of large numbers of old and young fish. Fishing pressure then reduced the number of old fish, while the younger fish remained in relatively high numbers, indicating a good survival rate from eggs to their first appearance in the fishery (recruitment).
However, with a further increase in fishing pressure, and poorer recruitment, the numbers of both old and young fish were reduced in the early to mid-1970's, dropping to their lowest level in 1976.
Strong conservation measures and improved recruitment enabled the rebuilding of the stock. The first sign of this was a dramatic increase in the numbers of young fish.
The significance of all this to the trap fishery is that the catch will to some degree reflect the size makeup of the total stock. Thus, it can be shown that the average size of cod taken in traps declined after the 1960's, reflecting the heavy fishing pressure on the northern cod stock. In recent years, 'however, there has been a general increase in the average length of trap cod. (Although this was not evident in the 1982 trap fishery because of the appearance of the relatively abundant 1978 year-class, which brought a lot of young, small fish into the traps.) Once the stock is fully rebuilt, the average size of trap cod will still, of course, be smaller than cod taken by other gears.
64~37 The most important part of a cod trap in regulating the size of the fish which it catches is the back or 'drying' twine. Regulations require that no mesh in a trap be smaller than 3.5 inch extension measure. In most cod traps only the back, the bottom and the first two or three fathoms of the sides attached to the back have 3.5 inch mesh.
The above detailed discussion of the inshore fishery is to clarify the need for an improved means for providing a steady, year-round, supply of saleable cod.
According to the present invention, after the live codfish have been captured, they will be placed in a temporary confinement means such as a tank filled with sea water, installed in a seagoing vessel, or land vehicle such as a truck.
During the transportation of captured codfish it is very important to control the temperature of the sea water so that the temperature is maintained at a low temperature in the range in which said codfish are able to exist, such as from minus 3.4C to 8C, preferably minus 1.5C to 5C, or sometimes 4C.
elides the temperature control it is also necessary to regulate molecular oxygen dissolved in the water to maintain suitable living conditions for the fish during confinement of said codfish on the vessel, and also to control salinity, light and fish-density on said vessel to maintain suitable optimum levels. In one of the embodiments of the present invention such seagoing vessel is a tank boat provided with refrigeration means for controlling the temperature of the sea water. The control of oxygen is provided by a supply of air, or preferably an oxygen tank installed on the tank boat. On this boat codfish captured by "cod traps" as mentioned above can be transported for considerable distances provided that the fish are kept in conditions close to their native environment without any injury or damage.
Sue By the present method captured live codfish are transported in the tank boats to an area provided with a permanent confinement means as shown in Figs. 4 an 5, which is provided for rearing and harvesting of said codfish.
Referring now to Figs. 4 and 5 there is shown in one embodiment of the present invention a fish farm system which comprises a number of floating net pens 10 connected to an existing wharf through fixed ramp 11, decked timber crib 14 and hinged ramp 12. The floating pens comprise net cages 16 attached to the railing 20 and supported on the water by means of floating elements 18. All of the floating pens 10 are anchored to the sea bottom by anchor means 20 to keep the pens in a stable condition. The fish farm system shown in Figs. 4 and 5 is provided with a main mooring system and a secondary mooring system and is placed with regard to the principal wind/wave direction.
For convenience of services, the system is provided with walkways for use by personnel of the farm system.
The process of rearing the codfish in said floating pens may desirably be accompanied by a process of storing and/or rearing of capelin fish which is one of the most important sources of food for codfish. The live capelin fish obtained from fishing grounds or nurseries are also placed in floating pens similar to those used for codfish and are supplied to the cod pens 10 as needed for feeding the codfish. Besides the use of capelin fish there could be used any other known nutrients to help codfish to grow to marketable size.
By this process, toe large catches of undersized and low-quality inshore trap cod presently caught by Newfoundland inshore fishermen in June and July when the market is at its worst and which do not bring Good returns to either fishermen or fish processors would be transformed into the equivalent of an annual source of cheap, large hatchery-raised cod (much larger than ~22~ 37 "fingerlings"). The on-growing of these "fingerlings"
produces a top-quality product available on a regular basis to the market, particularly in the winter when supplies of fish from the regular fishery art very scarce.
The weight of the cod by market time may well be over twice that of the live cod purchased from fishermen at the cod trap. Consequently, much higher prices can be paid to fishermen than at present when smaller fish are culled out and dumped and when boat quotas are often imposed on fishermen because fish processing plants are oversupplied with fish during the short trap season.
The concept can be expected to generate a great deal of renewed interest by inshore fishermen in the cod trap fishery and result in higher landings due to the fishermen ability to dispose of as much cod as can be taken (and at good prices).
As can be seen, Newfoundland's unique hydrographic conditions can ensure a large supply of live juvenile and larger cod for cod farming purposes. Nowhere else in the world is a trap cod fishery feasible (with the exception of a stretch of the North Shore of the Gulf of St. Lawrence in the Province of Quebec).
The raising of fin fishes on a large scale in floating net pens and general questions of fish nutrition and disease are under rapid development around the world, especially in the Norwegian salmon farming industry. Some of this technology and basic approaches can be applied to cod farming.
At the present time experiments to raise cod in captivity are under way in Norway. However, like the commercial Norwegian salmon farming industry, Norway's current noncommercial experiments with cod are based on the ingrowing of hatchery-raised fingerlings and cannot be compared to the concept of cod farming.
While the instant invention has been shown and described herein in what are conceived to be the most ~lZ26'~37 practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope ox the appended claims.
There is known a method of fish farming disclosed in Canadian Patent 1,172,115 which makes use ox a phenomenon observed with salmon, that is base on the fact that such fish prefer to stay under a light blocking cover and can be trained to stay under cover; and this method Lo can obviate the need for a conventional cage or other enclosing constructions.
There is also known another method of aquiculture of fish disclosed in Canadian Patent 1,041,849 which comprises establishing an aqueous euphoric zone in an enclosed body of water containing phytoplankton in said body of water above an aqueous bottom zone with the provision of nutrients in the said euphoric zone sufficient to cause growth of phytoplankton, and disposing a filter-feeding aquatic non-air breathing species in the body of water which will feed upon said phytoplankton and upon which said carnivorous species will feed, introducing said carnivorous species into said body of water.
Also known is a method of raising and harvesting fish as disclosed in Canadian Patent 945,845 wherein the fish are directed to the food source by an artificially created current. This results in the fish eating more food thereby reaching the desired size and weight in a shorter period of time. Growth of the fish is further enhanced by providing mechanism for aerating the water to assure the availability of an adequate supply of oxygen.
The invention described in that patent also provides for harvesting apparatus particularly adapted for use with the feeding apparatus which includes a container for confining the fish when they gather at the food source and structure for removing the confined fish from the container.
Previously all marine aquiculture methods and means have been confine to so-called "luxury" or high priced" species such as salmon or trout. This is largely -~lZ26 ~37 because the cost of producing hatchery-raised fingerlings is considered too high for species such as cod, haddock, flounder, sole, turbot, etc. (the so-called "white fishes").
Consequently, a high-volume "white fish"
a~uaculture industry capable ox competiting directly with other sources of meat such as mass-produced chicken has not been developed. Some work, however, has been done to create a hatchery system capable of the mass production ox cod fingerlings at a reasonable price.
The present invention represents a significant advance over the prior art by providing an efficient and cheap method of growing and harvesting cod.
Summary of The Invention In one embodiment the present invention resides in a method of aquiculture of codfish comprising the steps of:
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4C to 8DC preferably -1.5C to 4C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
Jo ., .
lZZ6~87 n another embodiment the present invention resides in a method of aquiculture of codfish comprising the steps of:
placing live codfish captured by coy trap means into temporary confinement means filled with sea water;
controlling the temperature ox said sea water so that said temperature is maintained within the range from -3~4C to 8C:
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said cod is in said temporary confinement means;
controlling light, and controlling fish density, in said temporary confinement means to maintain suitable lo optimum levels, transporting said captured jive codfish to a area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
placing live capelin captured by capelin trap means or capelin seine means into temporary confinement means containing sea water;
controlling the temperature of the water so that said temperature is maintained within the range of 0C to 8C;
regulating dissolved oxygen in the waters to maintain suitable living conditions for the capelin during confinement of said capelin in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels:
transporting said captured live capelin to an area provided with a permanent capelin storage or confinement means;
placing said live capelin from said temporary capelin A confinement means into an area provided with a permanent I' ~.Z'26~137 capelin confinement means provided for storing, and/or rearing; and or harvesting ox said capelin;
placing said capelin fish from said capelin transporting means into said permanent confinement means for feeding said codfish; and harvesting members of said codfish which have grown to a desirable size.
In a further embodiment, the present invention resides in a method of a~uaculture of codfish comprising the steps of:
placing of live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water in the range from -3.4C to 8C by refrigeration means;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish, by oxygen tank means;
controlling light and controlling fish-density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
In accordance with certain aspects of the present invention codfish are normally captured by means of cod traps.
The cod, when caught, are normally located at the bottom of the trap in a 4C to 6C band of water and, therefore, normally have a body temperature of 4C to ~:~Z6'~87 6C. There may be some advantage in depressing their body temperature below this level when they are placed into the well-boat.
The reasons for this are natively simple The body temperature of cod, like all poikilothermous vertebrates, can adjust passively to that of the surrounding water, as long as the rate of change of body temperature is not too great and/or other stress factors are not present.
In addition, and most importantly, oxygen consumption by the cod, which is a primary consideration in optimizing transport densities in the well boat from the trap to the farm, is lowered with decreasing water temperature.
In the present invention the temporary confinement means are normally sea water tans installed on a seagoing vessel such as a ship or large. On other situations it may be desirable to install temporary confinement means on a land vehicle such as a truck for expeditious delivery, for example in the case of a peninsula where the land trip would be much shorter than the trip by sea.
The permanent confinement means comprises a fish rearing enclosure such as a floating net pen placed in the open sea, preferably in a protected location. In a preferred embodiment of the invention the food supply to feed the codfish comprises Chaplin fish, which may be separately reared in an enclosure and then transported to the cod rearing enclosure serving as the permanent confinement means for the codfish, for feeding said codfish as required.
The present invention will now be described in further detail, with reference to the accompanying drawings, wherein:
Fig. 1 shows a notified Newfoundland cod trap:
Fig. 2 shows a typical inshore summer water temperature profile off ~ewfoundland's east coast;
~ZZ~87 Figs. 3 shows a water temperature profile off the east coast of Newfoundland in August, depending on weather conditions:
it. 4 is a plan view of a fish farm system according to one embodiment of the present invention; and Fig. 5 is a side elevation of a fish farm system as shown in Fig. 4.
The invention will now be explained in some detail, with reference to what is shown in the drawings.
The first step of the invention comprises catching live codfish in a suitable water layer, generally having a predetermined temperature and intensity of light which is favorable to cod. The catching means for this method could be a cod trap as shown in Fig. 1 which is a cod trap in use in Newfoundland and Labrador.
This and much of the other technical information set out in this specification and drawings can be found in a publication entitled "Trap Cod", published by the Communication Division, Canada Department of Fisheries and Oceans, Newfoundland Region, PRO. Box 5667, St. John's, Newfoundland Arc 5Xl, to which the present applicant is indebted.
The cod trap is a very efficient fishing gear, and can be very successful when used under the appropriate conditions. However, the trap fishery in Newfoundland has traditionally been plagued by serious problems. For example, catches can vary widely from season to season.
Also the trap catches mostly small fish. Catches in one year may be excellent, with fishermen jetting more fish than they can handle; in another year they may have great difficulty even scraping a "saving voyage". Catches in different areas may also show great variations.
The nature of the cod trap itself is one of the reasons for these fluctuations in catch. It is a stationary gear set in a specific location near the shore and must wait for the fish to come to it. About all a lZ~64~37 fisherman can do to improve the situation is move the trap to a new berth or shift it to deeper or shallower water in an existing location.
Thus, there are several possible reasons why the cod trap fishery experiences frequent failures, even though there may be plenty of fishermen, boats and traps employed to ensure a successful season.
Codfish prefer to inhabit water with a temperature of about OKAY to 8C, preferably I to 4C or lo SAC, although very small cod will tolerate somewhat warmer or colder water. Generally speaking the larger the codfish the deeper the water it prefers to live in.
figure 2 of the attached drawings illustrates typical inshore/near-shore water temperature conditions in Newfoundland waters and indicates what size cod are most likely to be taken (and the gear most likely to be used) at various water depths.
Of the many factors which can directly affect cod trap catches, probably the most important are hydrographic conditions. The most important of these are generally water temperature, currents or tides, and sea conditions.
Off the east coast of Newfoundland during the winter, the temperature of all inshore waters is likely to be about -1C to -1.5C. As the spring and summer advance, ice melts or moves off, the air gets increasingly warmer and surface water temperature starts to rise.
There are six rather simple, 'average' situations for a year that started with a late, cold spring, making for a cold trap season. The six situations are: 1) cold June, light variable or light onshore winds; 2) late June, strong offshore winds; 3) late June, strong onshore winds;
4) cold July, light variable or light onshore winds; 5) late July, strong offshore winds; 6) late July, strong onshore winds.
A typical situation in the month of June in a warm year with moderate onshore winds prevailing would be Jo ~l2Z64~'7 as follows. There is a warm layer of water, unsuitable for cod, about eight fathoms deep. Beneath that is a suitable layer going down to about 15 fathoms, with colder water lying beneath that. This is similar to the situation for a cold July with light onshore winds but it is somewhat better. The cod will now be congregated in a narrow layer between roughly 8 and I fathoms down, in good average trap depth. These conditions can mean good fishing for most traps and they could prevail right up into August or even later.
A situation which we might find in August in a cold year with light to moderate onshore winds prevailing is similar to the situation for a cold July with heavy onshore winds. The warm surface layer of water is not pushed quite as deep, however; it is down to only about 10 fathoms. The suitable layer for cod extends from 10 fathoms to about 23 fathoms deep. This might cut the cod off from traps in the 12-fathom depth range, but it should mean good fishing for deeper traps, as on the Avalon Peninsula, say, where the traps are usually set in the 18 to 20 fathom range.
Figure 3 of the attached drawings shows a typical kind of late-season situation. It might be found in August on a warm year with heavy onshore winds prevailing:
or in September on a cold year with heavy onshore winds or in September on a warm year with light to moderate onshore winds. In any case, either the summer temperatures or the onshore winds, or a combination of both, has by August or September created a deep surface layer of warm water extending down to about 13 fathoms or more. By this time, the water layer suitable for cod has likewise been pushed downward to about 40 fathoms. This is the end of the season for most trap fishermen, as the cod are now too deep for all but the deepest traps. The capelin have gone and the cod tend to be widely dispersed over a large bottom area, feeding off crab, shrimp and So ISSUE
other bottom living creatures. These conditions generally make for successful line trawl and near-shore gill net fisheries. It should be noticed that the deep water layer suitable for cod found at about the l00 fathom depth is a very stable one, and the long line and gill net fisheries conducted in this water is seldom, if ever, affected by the sort of hydrographic conditions described above.
Obviously, there is an almost endless number of situations that can arise. And things can be further lo complicated by local shoreline and bottom conditions, as they affect wind direction, currents, wave action and so on.
Observant fishermen, however, will soon recognize general patterns in the conditions in their particular areas. Those with a good basic understanding of the effects of winds and temperatures on the waters in their area may be able to take advantage of changing conditions to shift trap locations, or change to other gears from time to time, and so improve their chances of increasing their season's landings.
One piece of equipment needed to take advantage of changes in hydrographic conditions is a reversing water thermometer. By using the thermometer, a fisherman can determine the temperature of the water at different depths and set his trap at whatever depth has a suitable temperature range for cod (or change to another type of gear such as the line trawl).
Besides hydrographic conditions there are many other factors, which can make for a bad year, or two or three in a row (or particularly good years too, for that matter), in a local area or along an entire coastline.
For instance, if the overall size of the stock being fished is down, then chances are that trap catches will be down (along with catches by other gears as well).
Or the overall size of the stock may be quite large, but the stock might contain low numbers of the small size of 3l22~;48~
cod that are normally caught in traps. The amount of capelin that come inshore to spawn can affect trap landings, so can the amount of capelin that stay offshore because they are too young to spawn. The amount of sunlight, the presence of 'dirty water' and the spawning time of the cod are other factors which can help make or break a trap fisherman's season.
A successful inshore fishery requires a good supply of cod offshore in the range of sizes normally caught in the traps. The size of the northern cod stock is currently estimated to be about 1,500,000 t (metric tones), which should provide good catches inshore.
Sometimes the spawning in a particular year is not successful because of adverse ocean condition and few cod are born of that year-class. (A year-class is the cod born in a particular year; cod born in 1980, for example, would form the 1980 year-class.) Year-class success or failure is vital to the trap fishery. When two year-classes in succession are failures, there is a shortage several years later of cod in the traps and inshore generally, since it is cod of four to six years old that form the major portion of trap catches.
The inshore cod trap fishery takes place during the inshore spawning migration of capelin, which at this time are the major source of food for inshore cod. A lack of capelin in a local area could discourage cod from staying there They could move to other areas or into deeper water to search for food. However, the presence of large quantities of capelin in an area does not automatically ensure a good trap fishery. Conception and Trinity Bay fishermen experienced a poor trap fishery in recent years despite the fact that there were plenty of capelin in the bays.
During prolonged periods of bright sunlight, larger cod tend to move close inshore only during the night. During the day, they will move off to deeper 226~37 water, out of cod trap depth, to escape the light. The much smaller cod can endure brighter light, however, and Turing periods ox bright sunlight, only these very small wish, tweaked size, wit} stay in the area of the cod traps. The effect of sunlight is most pronounce when the water is very clear and calm and the light goes deeper than usual, making it possible to see bottom where normally it cannot be seen.
It should be mentioned that the following are main factors influencing the size of fish caught in a cod trap: mesh size, relative numbers of large and small fish which come in contact with the trap, relative numbers of large and small fish in the population or stock of cod being fished and geographical location of fishing effort.
Mesh size is important in determining the size of the fish which will escape and the size of those that will remain in the trap. We refer to this process as the mesh selection or selectivity of the trap.
Because the fish are brought on board toward the back of the trap, it is mainly through the back panel, and the side panels joined to the back, that they try to get away. Generally speaking, therefore, it is possible to influence the size of cod held in a trap by varying the mesh size used at the back of the trap.
Compared to other gears used in the inshore fishery, the cod trap tends to catch the smallest fish, mainly because smaller fish tend to be closer to shore where most cod traps are set. However, there are variations from year to year in the relative amounts of small and larger fish caught. Water temperatures or distribution and abundance of food may bring more large cod within range of the traps in some years. In certain areas, such as around headlands, deep water may run close to shore, and in such places larger cod may come within range of traps; traps set in deep water tend to catch a larger run of fish. Traps set in the bottom of bays, ~26~
where little trapping was cone until recently, tone to catch smaller fish.
It a cod stock is in a healthy or stable condition, all age groups, older ages in particular, will probably be abundant . As a stork it f idea it is usually the older, larger fish that get caught first. Overfishing plus poor survival of young fish reduces the population of both old and young wish. As the stock rebuilds, small fish in the younger age groups are more numerous.
This process has occurred with the 'northern' cod stock. In the early 1960's, before heavy fishing pressure, this stock was made up of large numbers of old and young fish. Fishing pressure then reduced the number of old fish, while the younger fish remained in relatively high numbers, indicating a good survival rate from eggs to their first appearance in the fishery (recruitment).
However, with a further increase in fishing pressure, and poorer recruitment, the numbers of both old and young fish were reduced in the early to mid-1970's, dropping to their lowest level in 1976.
Strong conservation measures and improved recruitment enabled the rebuilding of the stock. The first sign of this was a dramatic increase in the numbers of young fish.
The significance of all this to the trap fishery is that the catch will to some degree reflect the size makeup of the total stock. Thus, it can be shown that the average size of cod taken in traps declined after the 1960's, reflecting the heavy fishing pressure on the northern cod stock. In recent years, 'however, there has been a general increase in the average length of trap cod. (Although this was not evident in the 1982 trap fishery because of the appearance of the relatively abundant 1978 year-class, which brought a lot of young, small fish into the traps.) Once the stock is fully rebuilt, the average size of trap cod will still, of course, be smaller than cod taken by other gears.
64~37 The most important part of a cod trap in regulating the size of the fish which it catches is the back or 'drying' twine. Regulations require that no mesh in a trap be smaller than 3.5 inch extension measure. In most cod traps only the back, the bottom and the first two or three fathoms of the sides attached to the back have 3.5 inch mesh.
The above detailed discussion of the inshore fishery is to clarify the need for an improved means for providing a steady, year-round, supply of saleable cod.
According to the present invention, after the live codfish have been captured, they will be placed in a temporary confinement means such as a tank filled with sea water, installed in a seagoing vessel, or land vehicle such as a truck.
During the transportation of captured codfish it is very important to control the temperature of the sea water so that the temperature is maintained at a low temperature in the range in which said codfish are able to exist, such as from minus 3.4C to 8C, preferably minus 1.5C to 5C, or sometimes 4C.
elides the temperature control it is also necessary to regulate molecular oxygen dissolved in the water to maintain suitable living conditions for the fish during confinement of said codfish on the vessel, and also to control salinity, light and fish-density on said vessel to maintain suitable optimum levels. In one of the embodiments of the present invention such seagoing vessel is a tank boat provided with refrigeration means for controlling the temperature of the sea water. The control of oxygen is provided by a supply of air, or preferably an oxygen tank installed on the tank boat. On this boat codfish captured by "cod traps" as mentioned above can be transported for considerable distances provided that the fish are kept in conditions close to their native environment without any injury or damage.
Sue By the present method captured live codfish are transported in the tank boats to an area provided with a permanent confinement means as shown in Figs. 4 an 5, which is provided for rearing and harvesting of said codfish.
Referring now to Figs. 4 and 5 there is shown in one embodiment of the present invention a fish farm system which comprises a number of floating net pens 10 connected to an existing wharf through fixed ramp 11, decked timber crib 14 and hinged ramp 12. The floating pens comprise net cages 16 attached to the railing 20 and supported on the water by means of floating elements 18. All of the floating pens 10 are anchored to the sea bottom by anchor means 20 to keep the pens in a stable condition. The fish farm system shown in Figs. 4 and 5 is provided with a main mooring system and a secondary mooring system and is placed with regard to the principal wind/wave direction.
For convenience of services, the system is provided with walkways for use by personnel of the farm system.
The process of rearing the codfish in said floating pens may desirably be accompanied by a process of storing and/or rearing of capelin fish which is one of the most important sources of food for codfish. The live capelin fish obtained from fishing grounds or nurseries are also placed in floating pens similar to those used for codfish and are supplied to the cod pens 10 as needed for feeding the codfish. Besides the use of capelin fish there could be used any other known nutrients to help codfish to grow to marketable size.
By this process, toe large catches of undersized and low-quality inshore trap cod presently caught by Newfoundland inshore fishermen in June and July when the market is at its worst and which do not bring Good returns to either fishermen or fish processors would be transformed into the equivalent of an annual source of cheap, large hatchery-raised cod (much larger than ~22~ 37 "fingerlings"). The on-growing of these "fingerlings"
produces a top-quality product available on a regular basis to the market, particularly in the winter when supplies of fish from the regular fishery art very scarce.
The weight of the cod by market time may well be over twice that of the live cod purchased from fishermen at the cod trap. Consequently, much higher prices can be paid to fishermen than at present when smaller fish are culled out and dumped and when boat quotas are often imposed on fishermen because fish processing plants are oversupplied with fish during the short trap season.
The concept can be expected to generate a great deal of renewed interest by inshore fishermen in the cod trap fishery and result in higher landings due to the fishermen ability to dispose of as much cod as can be taken (and at good prices).
As can be seen, Newfoundland's unique hydrographic conditions can ensure a large supply of live juvenile and larger cod for cod farming purposes. Nowhere else in the world is a trap cod fishery feasible (with the exception of a stretch of the North Shore of the Gulf of St. Lawrence in the Province of Quebec).
The raising of fin fishes on a large scale in floating net pens and general questions of fish nutrition and disease are under rapid development around the world, especially in the Norwegian salmon farming industry. Some of this technology and basic approaches can be applied to cod farming.
At the present time experiments to raise cod in captivity are under way in Norway. However, like the commercial Norwegian salmon farming industry, Norway's current noncommercial experiments with cod are based on the ingrowing of hatchery-raised fingerlings and cannot be compared to the concept of cod farming.
While the instant invention has been shown and described herein in what are conceived to be the most ~lZ26'~37 practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope ox the appended claims.
Claims (12)
1. A method of aquaculture of codfish comprising the steps of:
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4°C to 8°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water so that said temperature is maintained within the range from -3.4°C to 8°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
2. A method of aquaculture of codfish comprising the steps of:
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said water so that said temperature is maintained within the range from -3.4°C to 8°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels;
transporting said captured live codfish to an area provided with a permanent confinement means:
placing said live codfish from said temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish;
placing live capelin captured by capelin trap means or capelin seine means into temporary confinement means containing sea water;
controlling the temperature of the water so that said temperature is maintained within the range of 0°C to 8°C;
regulating dissolved oxygen in the waters to maintain suitable living conditions for the capelin during confinement of said capelin in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels;
transporting said captured live capelin to an area provided with a permanent capelin storage or confinement means;
placing said live capelin from said temporary capelin confinement means into an area provided with a permanent capelin confinement means provided for storing, and/or rearing: and for harvesting of said capelin;
placing said capelin fish from said capelin storage means into said permanent cod confinement means for feeding said codfish; and harvesting members of said codfish which have grown to a desirable size.
placing live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said water so that said temperature is maintained within the range from -3.4°C to 8°C;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels;
transporting said captured live codfish to an area provided with a permanent confinement means:
placing said live codfish from said temporary confinement means in said permanent confinement means provided for rearing and harvesting of said codfish;
placing live capelin captured by capelin trap means or capelin seine means into temporary confinement means containing sea water;
controlling the temperature of the water so that said temperature is maintained within the range of 0°C to 8°C;
regulating dissolved oxygen in the waters to maintain suitable living conditions for the capelin during confinement of said capelin in said means;
controlling light and controlling fish density in said temporary confinement means to maintain suitable optimum levels;
transporting said captured live capelin to an area provided with a permanent capelin storage or confinement means;
placing said live capelin from said temporary capelin confinement means into an area provided with a permanent capelin confinement means provided for storing, and/or rearing: and for harvesting of said capelin;
placing said capelin fish from said capelin storage means into said permanent cod confinement means for feeding said codfish; and harvesting members of said codfish which have grown to a desirable size.
3. Method according to claim 1 or 2 wherein controlling the temperature of said sea water in said temporary confinement means is effected by circulating of said sea water from the sea.
4. Method according to claim 1 or 2 wherein controlling the temperature of said sea water in said temporary confinement means is effected by cooling of said sea water by refrigeration means and aeration of said water is effected by oxygen tank means.
5. Method according to claim 1 or 2 wherein controlling light and fish density in said temporary confinement means is effected, to achieve normal ambience for the cod, and is additionally accompanied by controlling salinity of said sea water by means of addition of a predetermined amount of fresh water to said temporary confinement means.
6. A method of aquiculture of codfish comprising the steps of:
placing of live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water in the range from -1.5°C to 8.4°C by refrigeration means;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish, by oxygen tank means;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
placing of live codfish captured by cod trap means in temporary confinement means filled with sea water;
controlling the temperature of said sea water in the range from -1.5°C to 8.4°C by refrigeration means;
regulating dissolved oxygen in the water to maintain suitable living conditions for the codfish during confinement of said codfish, by oxygen tank means;
controlling light and fish density in said temporary confinement means to maintain a suitable optimum level;
transporting said captured live codfish to an area provided with a permanent confinement means;
placing said live codfish from said temporary confinement means into said permanent confinement means provided for rearing and harvesting of said codfish;
supplying said codfish placed in said permanent confinement means with nutrient elements necessary for bringing said codfish into marketable conditions; and harvesting said codfish which have grown to a desirable size.
7. Method according to claim 1 wherein said temporary confinement means are movable in the open sea.
8. Method according to claim 1 or 2 wherein said temporary confinement means are installed on a seagoing vessel or truck.
9. Method according to claim 1 wherein said permanent confinement means comprises a fish rearing enclosure to provide an enclosed space for accommodating fish to be reared.
10. Method according to claim 4 wherein said fish rearing enclosure comprises a floating net pen placed in the open sea.
11. Method according to claim 1 or 2 wherein said temperature range is provided by refrigeration means installed in said temporary confinement means.
12. Method according to claim 1 or 2 wherein said oxygen conditions are provided by oxygen tank means installed in said temporary confinement means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000534905A CA1226487A (en) | 1987-04-16 | 1987-04-16 | Cod farming system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000534905A CA1226487A (en) | 1987-04-16 | 1987-04-16 | Cod farming system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1226487A true CA1226487A (en) | 1987-09-08 |
Family
ID=4135451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000534905A Expired CA1226487A (en) | 1987-04-16 | 1987-04-16 | Cod farming system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1226487A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2109884A1 (en) * | 1995-11-17 | 1998-01-16 | Tuna Farms Of Mediterraneo S L | Method for catching, towing and breeding tuna in the sea |
| CN103168730A (en) * | 2013-03-19 | 2013-06-26 | 大连海洋大学 | Pacific codfish artificial hatching method |
| CN110235812A (en) * | 2019-06-18 | 2019-09-17 | 中国水产科学研究院东海水产研究所 | A kind of polyculture method of round spot halibut and turbot |
| CN111771769A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, packaging and transportation method for cold water fish |
| CN111771770A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, packaging and transportation method of freshwater fish |
| CN111771768A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, package and transportation method for fresh and alive marine fishes |
| CN112005935A (en) * | 2020-09-03 | 2020-12-01 | 广州海尊电子科技有限公司 | Transfer method for improving survival rate of commercial fish during re-cultivation |
-
1987
- 1987-04-16 CA CA000534905A patent/CA1226487A/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2109884A1 (en) * | 1995-11-17 | 1998-01-16 | Tuna Farms Of Mediterraneo S L | Method for catching, towing and breeding tuna in the sea |
| CN103168730A (en) * | 2013-03-19 | 2013-06-26 | 大连海洋大学 | Pacific codfish artificial hatching method |
| CN110235812A (en) * | 2019-06-18 | 2019-09-17 | 中国水产科学研究院东海水产研究所 | A kind of polyculture method of round spot halibut and turbot |
| CN111771769A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, packaging and transportation method for cold water fish |
| CN111771770A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, packaging and transportation method of freshwater fish |
| CN111771768A (en) * | 2020-06-30 | 2020-10-16 | 唐山市活鲜农业科技有限公司 | Temporary culture, package and transportation method for fresh and alive marine fishes |
| CN112005935A (en) * | 2020-09-03 | 2020-12-01 | 广州海尊电子科技有限公司 | Transfer method for improving survival rate of commercial fish during re-cultivation |
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