ROHR and GUTHERZ: BIOLOGY OF MERLUCCWS ALBIDUS 



2 2.0- 



460 550 



METERS 



FIGURE 3. — Ratio of male to female Merluccius albidus de- 

 creases with increasing depth. 



=- 1.0- 



DE6REES CENTIGRADE 



FIGURE 4. — Average weight of individual Merluccius albidus vs. 

 bottom temperature for 278 trawl stations in the Gulf of Mexico. 



An increase in size of M. albidus with increasing 

 depths and decreasing temperature was observed 

 in the present study (Figures 2, 4; Table 3). 



REPRODUCTION 



Fecundity data of M. albidus were not collected; 

 however, a partially spent 680-mm SL female 

 taken on the De Soto Canyon slope in August 1970 

 yielded an estimated 340,000 greenish-white eggs 

 weighing 340 g. Advanced eggs in the ovaries of M. 

 productus ranged from 80,000 in small, 350 mm 

 SL, to 496,000 in large, 690 mm SL, specimens 

 (MacGregor 1966). Since the estimated number of 

 eggs in the specimen of M. albidus is somewhat 



similar to that of M. productus, the fecundity of the 

 two species may be similar. 



A spawning period extending from late spring to 

 early autumn is hypothesized forM. albidus in the 

 Gulf of Mexico and Caribbean Sea. Ripe fish were 

 observed as early as May and as late as October. 

 Running ripe males and females were taken 

 together in September 1973 on the Mississippi 

 Delta and De Soto Canyon slope (Table 4). 

 Females caught in February were in an advanced 

 resting stage, i.e., gonad maturation stage 4. 

 Spawning occurs in New England from April to 

 July (Colton and Marak 3 ). Some species of Mer- 

 luccius spawn throughout much of the year, 

 although most have a short spawning period 

 varying in time for individual species (Grinols and 

 Tillman 1970). 



Gonad maturation data suggest that spawning 

 occurs near the bottom in depths of 330 to 550 m. 

 Limited numbers of ripe fish were taken during 

 cruises which surveyed both the upper and lower 



3 Colton, J. B., Jr., and R. R. Marak. 1969. Guide for identifying 

 the common planktonic fish eggs and larvae of continental shelf 

 waters, Cape Sable to Block Island. Biol. Lab., Woods Hole, 

 Mass. Lab. Ref. 69-9, 15 Sept. 1969. 



TABLE 4. — Date, area, and depth at which ripe Merluccius 

 albidus have been collected in the Gulf of Mexico. 



TABLE 3. — Range and mean fishing depths, bottom temperatures, lengths, and weights of Mer- 

 luccius albidus sampled on the De Soto Canyon slope north of Tampa, Fla., in June 1971. 



151 



