The following steps pertain to methods for sorting the catch of a fishery research vessel such that the catch composition, both by weight and number of each species (group) can be established.
| Step 1 | Remove all sea snakes and other venomous or otherwise dangerous animals. Also remove turtles, and if alive, return these to the sea. Record number and kind of animals removed. |
| Step 2 | Remove inorganic debris and plant material. Record type of material removed. |
| Step 3 | Remove the larger fishes that are readily visible and place them in a box. |
| Step 4 | Wash the remainder of the catch (of small fish) if necessary, and mix with shovels. |
| Step 5 | Put the mixed catch in boxes, while continuing to remove larger fishes and putting them in the box mentioned in Step 3. The boxes should be filled simultaneously, not one after the other, and it should be made certain that all boxes contain the same weight of fish. |
| Step 6 | Count the number of boxes with small fishes and record. |
| Step 7 | A rule of thumb is to take one box out of every five at random for subsampling. Record number of boxes taken for subsampling as B1, B2, B3, etc. |
| Step 8 | The box(es) taken for subsampling is (are) then treated as follows: |
| - weigh the total catch in B1 and record; | |
- place fish of B1 on a sorting table and sort to species level as far as food
fishes and valuable crustaceans (e.g., shrimp) are concerned, and to taxonomic
groupings as well-defined as possible (e.g., genus, family, etc.), for the other
groups (the non-edible fishes and miscellaneous crustaceans); | |
| - repeat procedure, if appropriate for the other boxes (B2, B3, etc.). | |
| Step 9 | If more than one box were sorted, compute, for each species (or higher taxonomic group) the total weight and number in all sorted boxes. |
| Step 10 | Multiply the numbers and weight of fishes and invertebrate by species (or higher taxonomic group) by the ratio of the number of unsorted to sorted boxes. |
| Step 11 | Weigh and count the larger fishes mentioned in Steps 3 and 5, by species (very large fish should be weighed individually and measured). |
| Step 12 | Add, when there is an overlap (when the fishes of a certain species occurred both in the sorted boxes of small fishes and in the large fish box) the weights and numbers obtained in Step 11 to the weights and numbers in Step 10. |
| Step 13 | Step 12 (as well as Step 11, when there is no overlap) provide estimates of total catch, both in weight and number, by species or higher taxonomic groups. Record the totals, both in weight and numbers into an appropriate fishing log and convert to catch per hour if fishing time was less or more than one hour. During surveys, this step must be completed after each haul, or every evening at the latest, to preclude loss of information. |
| Step 14 | In addition to catch sampling, identifying and recording, the work of the fishery biologist generally includes among other things: |
| - collecting length frequency data; | |
| - collecting miscellaneous biological information on the fish caught, e.g., concerning their weight and maturity; | |
| - collecting and preserving specimens for further studies onshore; | |
| - collecting oceanographic data. | |
The methods generally used for the various activities in Step 14 are discussed in details in various manuals available from FAO, e.g., in Holden and Raitt (1974).
The procedure outlined here is adapted from Losse and Dwippongo (1977).
