The weather adjustments already computed have measured the effect 

 on daily catch=per=boat as an 8=-season average effect and, while reliable 

 over a long period^ are not accurate for short periods of time or for 

 specific daySo 



Adjus t for limits „ <= Processing plants^ at times, have limited the 

 amount of f i^TPreceivable from a boato Under these conditions, compliant 

 boats stop fishing when the limit is approximately attained and the av^ 

 erage catch must be less than if there had been no limito 



The adjustment for the effect of limits j however, is based on the 

 assumption that their principal effect is to shorten the period of fishing 

 per nighto When a limit catch is attained by a boat early in the night, 

 that boat's fishing effort should be figured as only a fraction of a nighto 

 This may be computed as the ratio of the actual, to the total available, 

 fishing timeo 



Accoimt is taken of boat^capacity, as well as imposed, limits* The 

 time of attaining limits is recorded only for the catches of boats whose 

 skippers are interviewed when a sample of fish is takeno This is only 

 a small fraction of the whole number but it is assumed that the average 

 time applies to the entire fleeto Due to the smallness of the sample^ 

 the adjustment is computed as an average for an entire lunar weeko It 

 is probably reliable for long, but not for short, periods o Complete 

 operational records for the boats would be better if these were available o 



Convert weight to number o - Catch statistics are always in terras of 

 weight, but data must be in ntanbers of fish for computation by the methods 

 of vital statistics o As the relationship of weight to number fluctuates 

 in accordance with size-composition, the conversion is made on a daily 

 basis o From a predetermined length=weight relationship, the average weight 

 of fish in the day's length=f requency distributions is computed and this 

 average weight divided into the pounds -caught-per-boat-day, coaverting 

 that statistic into ntjmbers-caught^per-boat-dayo For samples taken in 

 1941 ■=42 and subsequent seasons, the average weight is determined by direct 

 weighing of each sample o 



If now, we were to weigh each day's frequency by each day's numbers- 

 caught-per°boat=day and sum the frequencies for all ports and all days 

 for each season^ the resulting curves might be taken as representing the 

 relative abundance of each size of fish for the series of seasons and the 

 task of converting catch statistics into stock statistics be considered 

 complete o 



Indeed, Hodgson (1939) regarded this very process, less some of the 

 adjustments, as giving the relative abundance of each year^class in the 

 East Anglian herring fisheiyo To use an analagous method for the Pacific 

 sardine would be to assume either that? (l). The average boat's fishing 

 capacity was equal in the fleet of each port, or that an equal proportion 

 of the fish population was drawn upon by each ports and (2), the various 

 sizes of fish were available randomly from each port, or that the length 

 of time a complex of sizes of fish was available at each port was propor- 

 tional to the popuiationo Howeverj these assumptiors are either known or 

 suspected to be erroneous o Various further devices of weighting, ®©lec= 

 tion, and combination need be empioyedo 



