RU2450512C2 - Trapped method for evaluating stocks of water biological resources - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: method involves the definition of strathes of the test site of the water area, performance of the station of accounting catching, recording of the catch of traps, determination of the density of distribution of aquatic biological objects in the study area and assessment of stock of water biological resources according to the data obtained. The stations of accounting catching are performed with the possibility of catching with standardised traps with known given catchability and selectivity. When performing the stations the parameters of standardised traps are taken as control. In addition, a joint catching with traps is performed with different predetermined selective properties. The number and the selective properties of the traps are set and performed in accordance with the terms and objectives of accounting. The accounting of the catching is performed both for each trap individually and cumulatively for all traps with different selective properties. Catching with traps is performed together both in a certain strath and in different strathes.

EFFECT: technology enables to reduce the impact of the effect of "saturation" of traps on the catches.

3 cl, 4 dwg

Description

The invention relates to the fishing industry, in particular to methods for research and assessment of stocks of aquatic biological resources (FBG).

Valuation of FBG reserves is the main task of managing their operation. The main part of the FBG assessment is the conduct of survey surveys of aquatic biological objects. When organizing surveys, the principles of determining their number and temporal-spatial principles of determining the location of trap fishing stations are planned.

Surveying is reduced to measuring a number of certain parameters related to the determination of environmental conditions and the object of study (for example, oceanological), the density of the stock of the studied objects, i.e. catch attributed to the area or volume at stations covering the study area in a specific order.

A station means single trawling, or the order of traps or a set of separately set traps, or the point of underwater photography or direct visual observation in order to determine the distribution density of the studied object in the shooting area.

Stock density is understood as the number and biomass of the studied object in a certain area (stratum), caught for accounting fishing (for example, square kilometer, mile, etc. with clearly defined boundaries) and, as a result, over its entire habitat.

There are a number of known methods, including software, calculation of reserves of FBG using the data of accounting fishing.

For example, the area method is the simplest and most easily applicable way to estimate the stocks (total biomass) of sublittoral hydrobionts, and the stock is calculated as the product of the average number (biomass) and the area over which this species was discovered.

Due to the fact that applied fisheries science was not able to conduct large-scale trawl research works for a rather long time, the use of traps as a way to obtain scientific data was widespread. In addition, in some areas, the nature of the soil does not allow specific data on trawl catches, and sometimes trawling is not possible at all. The use of traps requires the development of an appropriate methodological approach to the analysis of such a material and the interpretation of the results obtained during accounting surveys (Biology of the equine-crab Lithodes atquispinus Benedict in the Kuril Islands / S.A. Niyazev: Ph.D., Yuzhno-Sakhalinsk, 2003 .-- 167 p.)

Known trap method for assessing the stock of crab (Tanner crab pot survey metods Southeats Alaska / Julie Bernarski, Gretchen Bishop and Chris Siddon: Alaska Departament of Fish and Game Division of Commercial Fisheries. - N 1J08-02. - 2008. - 8 p.).

The method provides for the implementation of the accounting catch of the crab in the studied specific area of the water area by setting a trap order, which includes standardized traps in order to minimize the fluctuation of catches in their size and size composition of the caught individuals. A standardized trap has strictly defined selective qualities and catchability.

Before setting the trap order, the areas of catching (strata) of hydrobionts are determined by the value of the expected catch for a standardized trap, the stagnation time. After raising the traps after a certain time, the catch of each trap is taken into account separately, the catch is measured, sorted by species, its biological parameters are evaluated.

The size composition of the stock according to the survey results is calculated on the basis of data from catches of standardized order traps with constant selective and trapping properties. It is assumed that the size composition of catches of such traps will be the same.

Accounting traps of only one type leads to the fact that some size classes of the fished object can be underestimated, because in the catch, any particular size grouping of the object will predominate predominantly, the catch of which is determined by the specified selective qualities of the traps. The results of studies on the number and size-age composition of the studied object obtained in this way will not accurately reflect the true size of its stock. In addition, fishing with such traps does not take into account the effect on the result of the effect of “saturating” the traps with a catch consisting of small individuals, as their number inside the trap increases, it frightens off other individuals from entering the trap.

The proposed trap method for assessing stocks of aquatic biological resources eliminates these disadvantages.

The method includes determining the strata of the studied area of the water area, performing a registration fishing station providing for fishing with standardized (standard) traps with known predetermined catch and selectivity, the parameters of which are taken as control ones, accounting for the catch of traps, determining the distribution density of aquatic biological objects and assessing the stock of aquatic biological resources received data.

When performing a station, fisheries of aquatic biological objects are carried out in the order of traps or separately installed traps.

To adjust the catches of standardized traps during station execution, traps with various specified selective properties are additionally trapped, while the number and selective properties of traps are set and performed in accordance with the accounting conditions and tasks, and the catch is recorded for each trap separately and in total for all traps with various selective properties that are caught on a particular stratum together.

Various selective properties of the traps are provided by changing the size and design of the traps, and / or the mesh size and shape of the mesh, and / or the size, shape and location of the inlet and selective outlet holes, and / or the presence of devices that prevent the exit of the trapped individuals, and / or the type and quality of the bait and its location in the trap.

Due to, for example, the presence of special selective holes and devices in the design of the trap, as well as an increase or decrease in the mesh size of the net cover, trapped individuals whose sizes are smaller than the size of the selective holes will leave the traps during fishing, for example, being repelled already trapped individuals from bait and from being trapped.

It is well known that the presence of selective devices in traps can reduce the effect of the saturation of traps with a catch consisting of small individuals as their number inside the trap increases (Effectivenes of crab and lobster traps / Miller Robert J. // Can. J. Fish. And Aquat. Sci. - 1990. - 47. - N 6. - S.1228-1251).

The practice of well-known studies by trap selectivity experts shows that this effect can also be eliminated or reduced by changing and adjusting other design parameters of the trap, such as the size and shape of the trap, the mesh size and shape of the mesh coating, the size and shape of the outlet and inlet openings, and their location trapped, the presence of devices preventing the exit of trapped individuals, the type and quality of the bait, its location in the trap (Xu and Millar 1993, Pengilly 2000, Zhou and Kruse 1999, Rumble at. All 2006, Miller 1977, Miller 1980, Miller 1983, Zh ou and Shirley 1997a.)

The technical result of the invention lies in the fact that researchers can obtain more reliable information about the number and size and age composition of the studied object in a certain water area, reduce the effect of saturation of traps on catches of the object.

The specified result is achieved by the fact that, according to the proposed method, when performing registration fishing stations on a certain area (stratum) together with standardized (standard) traps with known predetermined catchability and selectivity, the parameters of which are taken as control ones, traps with various specified selective properties are additionally performed . The number and selective properties of traps are set and performed in accordance with the conditions and tasks of accounting. At the same time, in the catch of each trap with different specified selective parameters (selectivity), individuals will be held by a mode of a certain size, as a result, the size range of their total catch will provide a more complete and accurate picture of the distribution density of the studied objects in the shooting area. In addition, the effect of saturation of traps on the catch is reduced. Thus, the catch data of standardized traps are corrected both on a specific stratum and on different strata.

Figure 1 presents a schematic representation of a standardized (standard) cone trap (side view and top) with dimensions in m; figure 2 is a schematic illustration of a conical crab trap with selective "window" (a) and a selective plate with a round hole "window" (b) with dimensions in mm; figure 3 is a diagram representing the share in% of a non-commercial size crab in catches of standard and traps with "windows" during stagnation: a - two days, b - 3 days, c - 4 days; 4 is a diagram representing the average number of commercial-sized males in a catch of a standardized (standard) trap and a “window” trap during stagnation: a - two days, b - 3 days, c - 4 days.

An example implementation of the method.

Experimental work was carried out during the fishing season within the 12-mile zone of the Barents Sea Bay, on rocky ground.

The object of fishing is the Kamchatka crab.

The strata of the study area were identified.

Recording fishing stations were made by setting eight separately set conical crab traps containing frame 1, net cover 2 with mesh 3 with a fishing size of more than 70 mm, of which 6 traps were standardized (standard, with known selective qualities and catchability, Fig. 1) and 2 — each was equipped with four selective “windows” 4 (Fig. 2a) made of fluoroplastic plates 4 (Fig. 2b) with a hole installed in the cutouts of the net shell 2 of the trap in order to keep the crabs in the trap in traps measure. The hole diameter was 145 mm. The stagnation time of the traps is 2, 3 and 4 days.

Freshly frozen Atlantic herring was used as bait.

Fishing was carried out at depths of 240-265 m.

During the period of experimental work, 29 stations were completed, trap catches were analyzed, 1283 specimens of Kamchatka crab were measured. The measurements of catches were carried out on board the vessel in accordance with the methods of the FSUE PINRO. The analyzed crab was returned to its natural habitat.

When the clusters of predominantly small crab with different lengths of stagnation of traps were caught, the proportion of non-commercial crab in standard traps and traps with selective “windows” was significantly different.

With a stagnation duration of traps from two to four days, the share of non-commercial size crab in the catches of standard traps was 96-98%, while in the catches of traps equipped with “windows”, a tendency to decrease the share of non-commercial crab from 86 to 50% was clearly observed ( figure 3).

The average carapax width of the crab in catches of traps with “windows” and standard traps was: when stagnant for 2 days - 120 mm and 100 mm, three days - 118 mm and 82 mm, four days - 122 mm and 92 mm, respectively. It was noted that traps without “windows” were faster filled with a small-sized crab, since a non-commercial-sized crab that got into the trap could not leave it, and a larger commercial-sized crab did not get inside due to the difficulty of entering the trap, because the known effect of “saturation” acted traps.

Thus, for different durations of stagnation of traps, their average catch per trap amounted to: commercial crab in standard traps from 0 to 2 specimens, in the catch of traps with "windows" - from 2 to 5 specimens (figure 4).

Obviously, the catch data for standard traps do not accurately reflect the abundance and size range of the studied objects, taking into account the data of the total catches of traps with selective “windows” makes it possible to correct these data and, as a result, present a more complete and accurate picture of the distribution density and size and age composition of crabs in the shooting area (stratum).

The observed results allowed us to conclude that in traps with selective “windows” there always remains room for unhindered penetration of commercial-sized crabs inside due to the presence of free exit of small-sized individuals through the “windows”. By adjusting the size of these holes, it becomes possible to control the size composition of the catch of the trap. Reducing the effect on the size of the catch of traps with “windows” of the effect of “saturation” of traps also corrects the catch data of standard traps both on a specific stratum and on different strata.

The assessment of crab stocks on the studied area was carried out using the area method, i.e. the stock was calculated as the product of the average abundance (biomass) and the area on which the crabs lived.

The additional use of selective devices in holding traps of hydrobionts in some traps of the same station to keep individuals of a certain size inside the traps made it possible to obtain more complete data on the number and size-age composition of the studied object in the studied water area.

Studies of selective trap fishing show that equally such results can be achieved by changing and regulating other parameters that affect the selective quality of the trap: design parameters of the trap, such as the size and shape of the trap, the size and shape of the mesh of the net cover, the size and shape of the output and inlets, their location on the trap, the presence of devices that impede the exit of salted individuals, the type and quality of the bait, its location in the trap.

The application of the proposed method will provide more reliable information about the stocks of objects in the studied water area, which in turn will allow more accurately assess and predict the value of the exploited stock, determine the total allowable catch and, accordingly, rationally use the stock, which will ultimately increase the profitability and effectiveness of regulation fishing of aquatic organisms.

Claims (3)

1. A trap method for assessing the stocks of aquatic biological resources, including determining the strata of the studied area of the water area, performing a registration fishing station providing for fishing with standardized traps with known preset catch and selectivity, taking into account the catch of traps, determining the distribution density of aquatic biological objects in the study area and assessing the stock of water biological resources according to the data obtained, characterized in that, when performing stations, the parameters of standardized traps are accepted mute for control, additionally carry out joint traps with traps with various specified selective properties, while the number and selective properties of traps are set and performed in accordance with the conditions and tasks of accounting, catch accounting is performed both for each trap separately and in total for all traps with different selective properties that are performed together, both on a specific stratum and on different strata. 2. The trap method for assessing stocks of aquatic biological resources according to claim 1, characterized in that when performing a station, fisheries of aquatic biological resources are carried out in the order of traps and / or separately set traps. 3. The trap method for assessing stocks of aquatic biological resources according to claim 1, characterized in that the various selective properties of the traps are provided by changing the size and design of the traps, and / or the mesh size and shape of the mesh coating, and / or the size, shape and location of the input and selective exit holes, and / or the presence of devices that impede the exit of salted individuals, and / or the type and quality of the bait and its location in the trap.

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