FISHERY BULLETIN: VOL. 75, NO. 1 



of approximately 667 x 10 3 tons in 1971 (Figure 

 2). Landings of herring and mackerel peaked in 

 1968 and 1972, respectively (International 

 Commission for the Northwest Atlantic Fisheries 

 1965-1973, 1974c, 1975a, see footnote 12). 



Landings for the remaining species groups 

 (Figure 3) generally reflect decreasing abundance 

 in response to increasing effort. Landings of 

 flounders were relatively constant but did in- 

 crease until 1969 followed by a gradual decline. 

 The somewhat anomalous 1969 value resulted 

 primarily from sharply increased catch of yellow- 

 tail by distant water fleets (Brown and Henne- 

 muth see foonote 6). Steadily declining landings of 

 other groundfish throughout the period of study 

 can be attributed in part to declining abundance, 

 while other pelagics and other fish show a general 

 increase which would appear to be associated with 

 increased effort as shown later. Squid landings 

 also increased sharply since 1970. 



As TAC's have been imposed for certain stocks 

 since 1970, their possible influence should be 

 considered. It is not believed, however, that quota 

 management affected these trends appreciably. 

 Species subject to quota management in 1970 and 

 1971 (i.e., haddock and yellowtail) had already 

 been seriously depleted, while in 1972 and 1973 

 TAC's did not appear to be limiting with the ex- 

 ception of those imposed for haddock, yellowtail, 

 and herring, and for the latter two species TAC's 

 were in fact exceeded (International Commission 

 for the Northwest Atlantic Fisheries 1975c). It 

 appears likely that TAC's imposed for 1974 had a 

 greater effect, particularly in the case of herring 

 and mackerel; also, the overall TAC of 923.9 x 10 3 

 tons (referred to above) undoubtedly limited total 

 catches by nation to some degree although it was 

 exceeded by approximately 75 x 10 3 tons (In- 

 ternational Commission for the Northwest At- 

 lantic Fisheries 1975c). In summary, however, it 

 would appear that the influence of quota 

 management on the overall trends depicted in 

 Figures 2 and 3 was relatively minor for the level 

 of effort being exerted which, as noted previously, 

 increased by a factor of six during the period 

 1962-72. It is not possible to speculate whether or 

 not significant additional effort would have been 

 added in 1973 and 1974 (say from new entrants to 

 the area), had there not been regulations. 



The possible influence of bias upon reported 

 landings remains to be mentioned. In ICNAF 

 statistical bulletins, some landings have been 

 recorded as "not specified," e.g., "groundfish (not 



specified)," "other pelagics (not specified)," etc. 

 Insofar as possible, we have combined these 

 landings with landings data reported by species 

 within each species group. In recent years, 

 however, an improvement has occurred in re- 

 porting accuracy which appears to have affected 

 the relative amounts of "not specified" landings 

 (and thus annual totals as depicted in Figures 2 

 and 3). For instance, examination of data in 

 ICNAF statistical bulletins (International 

 Commission for the Northwest Atlantic Fisheries 

 1965-1973, 1974c, 1975a) reveals a decrease in the 

 relative percentage of "not specified" groundfish of 

 from 15 to 20% of the other groundfish category in 

 the mid-1960's to approximately 10% in 1970-73, 

 while for "other fish" a complete reversal of this 

 trend occurred. The "not specified" proportion of 

 the total "other fish" category increased from 

 approximately 10% in the mid-1960's to 25-30% 

 during 1970-73. This implies that landings for 

 principal groundfish and other species may have 

 been erroneously included under other groundfish 

 to a greater extent in former years, thus biasing 

 the observed trend for other groundfish down- 

 ward, while the trend for other pelagics and other 

 fish may have been biased upward due to inclusion 

 of previously omitted landings data in more recent 

 years. The actual extent to which trends depicted 

 in Figures 2 and 3 were distorted by this factor is 

 problematical, but it should be noted that for 

 principal groundfish, principal pelagics, floun- 

 ders, and squid, more important (and/or more 

 readily identified) species were involved which 

 probably were not affected by reporting inac- 

 curacies to the same degree. Consequently, it is 

 our judgement that trends for the remaining 

 species groups were probably not appreciably 

 biased. 



CHANGES IN BIOMASS 

 Unweighted Analyses 



Summaries of survey data by species and area 

 permit preliminary evaluation of the magnitude 

 and direction of change in selected biomass 

 components in recent years and of the degree of 

 year-to-year variability that may be encountered. 

 Accordingly, we examined trends for different 

 species and strata sets and for data summed over 

 all strata before attempting transformation or 

 weighting procedures. 



Individual strata can be grouped for analysis on 



