FISHERY BULLETIN: VOL. 75, NO. 1 



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FIGURE 2. — A.) Stations in the survey area where eggs of 

 round herring were collected at least once during 1971-74. 

 Stations where eggs did not occur are indicated by dots. 

 B). Stations in the survey area where larvae of round herring 

 were collected at least once during 1971-74. Stations where 

 larvae did not occur are indicated by dots. 



egg abundances for each cruise at all stations, as 

 well as summaries for other clupeid species, have 

 recently been reported (Houde et al. 1976). 



Cruise means for round herring larvae ranged 

 from 0.00 to 20.29 under 10 m 2 (Table 1). At posi- 

 tive stations the cruise means for larvae ranged 

 from 4.44 to 175.07 under 10 m 2 (Table 1), but the 

 latter value was based on a single positive station 

 for cruise CL 7412. Excluding that cruise, the 

 highest mean larval abundance under 10 m 2 at 

 positive stations was 49.97. No stations had more 

 than 1,000 larvae under 10 m 2 during the 17 

 cruises. Tabulated station data on catches and 



abundance of round herring, and other clupeid 

 larvae, have been published (Houde et al. 1976). 



The survey area did not encompass the entire 

 spawning area of round herring in the eastern 

 Gulf. Eggs were collected at stations located farth- 

 est offshore on some cruises (Figures 3-6) but 

 abundance was less at stations deeper than 200 m 

 than at shallower stations. I believe that most of 

 the spawning area and spawning population was 

 included in the survey area, and that my egg 

 abundance estimates suffer only small biases be- 

 cause of failure to sample a part of the population. 



There was no apparent difference in the inten- 

 sity of round herring spawning at stations be- 

 tween 30 and 50 m deep compared with stations 

 deeper than 50 m. The log 10 mean abundance es- 

 timates of eggs under 10 m 2 of sea surface for all 

 positive stations =£50 m and for those >50 m were 

 calculated from pooled data of all cruises that had 

 round herring eggs. The «50 ra logio mean was 

 1.6351 (n = 25, Sj = 0.1609); the >50 m log 10 mean 

 was 1.5585 (n = 32, S; = 0.1209). These means did 

 not differ significantly (f-test;P>0.50). However, 

 the area between the 30- and 50-m depth contours 

 was less than that included between the 50- and 

 200-m contours. The total area between the 30- 

 and 200-m depth contours was considered to be the 

 spawning area; 40.1% of the area is in the 30- to 

 50-m zone while 59.9% is between 50 and 200 m. 

 Thus, the total abundance of eggs in the area 

 where depths exceeded 50 m probably was greater 

 than abundance in shallower areas. The 50-m 

 depth contour divides the shelf area in the eastern 

 Gulf into approximate halves. For eight cruises in 

 which sampling effort was distributed nearly 

 equally to include potential spawning area in 

 water =£50 m and >50 m (cruises 8C 71 13-TI 7114, 

 8B 7132-TI 7131-GE7127, 8B 7201-GE 7202, GE 

 7208, IS 7209, IS 7303, IS 7308, and IS 7320), the 

 summed totals of egg abundance from the areas 

 represented by stations on these cruises were 

 compared with respect to the 50-m depth contour. 

 A total abundance of 11.92 x 10 11 eggs was esti- 

 mated for stations =£50 m; total abundance was 

 16.73 x 10 11 at deeper stations. If these egg abun- 

 dance estimates reflect relative adult abundance, 

 then 41.6% of the adult population was located in 

 depths =£50 m and 58.4% was distributed at depths 

 >50 m. The total abundance of eggs, and appar- 

 ently of adult round herring, is directly propor- 

 tional to the surface area of the two depth zones. 

 Some small fraction of the spawning population 

 inhabited depths greater than those sampled in 



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