ESTIMATING ABUNDANCE OF SALMON FINGERLING 

 Howard S. Sears 



Estimating the abundance of pink salmon 

 ( Oncorhynchus gorbuscha) fingerlings by means of 

 various types of sampling gear was attempted in 

 1957 and 1958 in southeastern Alaska to establish 

 an index of abundance that could be used to predict 

 the size of future pink salmon runs. Fishing gear 

 tested during 1957 included beach seines, set gill 

 nets of variable mesh, an Isaacs Kidd midwater 

 trawl, and a Canadian meter hoop net. 



Insufficient numbers offish were taken by 

 these types of gear , and in 1958 experiments were 

 conducted with a lampara bait seine. Operations 

 were carried on in Ernest Sound and Clarence 

 Strait and in Revillagigedo Channel as far south 

 as Dixon Entrance. Results obtained were more 

 encouraging than with the other nets that had been 

 tested. 



A conventional lampara seine consists of 

 a large central bag or bunt section and two tapered 

 wings. It differs radically from the purse seine 

 in that its mesh size is not uniform, and there 

 are no purse rings or purse line. The bag section 

 is of smallmesh andis about one -fifth of the total 

 net length. The wings are tapered, and the mesh 

 varies from about 5 inches at the base to as much 

 as 14 and 16 inches at the wing tips. The function 

 of the large wing mesh is to guide fish into the bag 

 where they are held until the lead line is closed 

 by pulling both wings simultaneously. The foot 

 or lead line is considerably shorter than the cork 

 line. The net is hung so that it is in the shape of 

 a large scoop. 



The modified seine used in the 1958 ex- 

 periments was 120 fathoms long at the cork line, 

 96 fathoms long at the lead line, and 12 fathoms 



deep at the point where the bag and wing bases 

 meet. Mesh sizes were 6-inch, 6-thread Marlon 

 in the wings; 3-inch, 6-thread Marlon in the apron 

 (floor of net), and 1/2-inch, 26-thread Marlon in 

 the bag. Dry weight of the net was 285 pounds. 



The method of fishing differed from that 

 generally used by commercial bait seiners using 

 a conventional net. Their method is to make a 

 circling set from a towed skiff by paying out one 

 wing, which is anchored or buoyed, followed by 

 the bag and second wing. Setting of the net is com- 

 plete when the end of the first wing is retrieved. 

 Both wings are then pulled simultaneously until 

 the bag is brought close to the skiff. 



Instead of a single towed skiff , two 18-foot 

 flat bottom boats (called Cordova skiffs in Alaska) 

 powered by outboard motors were used in the 1958 

 experiments. The bag and one wing were placed 

 in one skiff, and the other wing was placed in the 

 second skiff. A large circling set was made by 

 setting the bag from the stern of the first skiff. 

 The wings were then payed out from the respec- 

 tive skiffs. After the wings were set, the two 

 skiffs towed the wing ends together. The wings 

 were then hauled aboard the skiffs. A schematic 

 viewof the modified lampara seine in fishing po- 

 sition is shown in figure 1. 



In the summer of 1958, 260 sets were made 

 with the lampara seine to evaluate its usefulness 

 in the prediction program. A total of 2,509 fing- 

 erling salmon of all 5 species were taken. The 

 higher catches of this type net over those used 

 heretofore suggest that it may be possible with 

 random sets to relate the average number of fing- 

 erling per seine haul to the number of returning 

 adults . 



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