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Fishery Bulletin 104(2) 



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JO 



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season. Therefore fecundity is very dif- 

 ficult to determine before the onset of 

 the spawning season because 1) there 

 is no way to differentiate between the 

 oocytes that are going to be shed dur- 

 ing the next season from those which 

 will remain for future seasons, and 2) 

 the number of reserve oocytes that will 

 mature during the next spawning season 

 cannot be predetermined (Hunter and 

 Goldberg, 1980; Hunter et al., 1985). To 

 estimate indeterminate annual fecun- 

 dity, the mean number of eggs per batch 

 and spawning frequency throughout the 

 spawning season must be calculated. Ow- 

 ing to the complexity of obtaining these 

 data, fecundity studies are normally lim- 

 ited to determinate spawners or pelagic 

 species of substantial economical inter- 

 est (Hunter and Goldberg, 1980; Hunter 

 and Macewicz, 1985a; Karlou-Riga and 

 Economidis, 1997; Murua et al., 1998). 



The blacktail comber (Serranus atricau- 

 da Gunther, 1874), is a littoral (3-150 m) 

 benthic species, ranging throughout the 

 eastern central Atlantic (from the Bay of 

 Biscay to Mauritania, the Azores, Madeira, 

 and the Canary Islands) and in the west- 

 ern Mediterranean. It is, therefore, a spe- 

 cies of wide distribution and commercial 

 interest in many regions (Bauchot, 1987; Smith, 1990). 

 In the Canary Islands, it is an economically important 

 species for small-scale inshore fisheries (Perez-Barroso 

 et al., 1993). Garcia-Di'az et al. (1999, 2002) determined 

 that this species is a functional simultaneous hermaphro- 

 dite. The ovary is classified as asynchronous, i.e., various 

 stages of oocyte development occur simultaneously (pri- 

 mary growth stage, yolk vesicle formation, vitellogenesis, 

 oocyte maturation, and mature egg). The histological 

 structure of the gonad and of the sperm indicates that 

 this species is an externally fertilizing teleost. 



The objective of this article is to increase our under- 

 standing of the reproductive biology of the blacktail 

 comber in the Canary Islands by estimating its spawn- 

 ing season duration, size at maturity, and fecundity. 



Materials and methods 



0' 15" 



Europe 



Atlantic Ocean 



Canary Islands 



500 km 



Location o 

 [Serranus 

 Atlantic). 



Figure 1 



f sampling areas (shown with dark shading) for blacktail comber 

 atricauda) specimens from the Canary Islands (eastern-central 



buffered formaldehyde. After 24-48 h, they were dehy- 

 drated, embedded in paraffin wax, sectioned in longi- 

 tudinal or cross-sections (4 to 5 .urn thick), and stained 

 with Harris "hematoxylin-Puttis" eosin. Oocyte stages 

 and spermatogenic cells were classified according to 

 Garcia-Diaz et al. (2002). Postovulatory follicles and 

 atresia were also characterized according to the crite- 

 ria used for Engraulis mordax by Hunter and Goldberg 

 (1980) and Hunter and Macewicz (1985b). Maturity 

 stages (MS) were determined from histological obser- 

 vations (the development of the ovary and testis and 

 also the presence and absence of different types of the 

 oocytes and spermatocytes) according to Garcia-Diaz 

 et al. (1997, 2002) (Table 1). The developmental stages 

 of the oocytes were categorized according to Selman 

 et al. (1993): primary growth (stage I); cortical alveoli 

 formation (stage II); vitellogenesis (stage III); oocyte 

 maturation (stage IV); and mature egg (stage V). 



Sampling 



A total of 425 individuals of S. atricauda. ranging from 

 15.7 to 43.2 cm total length were sampled monthly from 

 commercial catches off the Canary Islands between Sep- 

 tember 1992 and November 1994 (Fig. 1). 



Total length (TL), to the nearest centimeter, was 

 measured for each specimen, together with the total 

 and gutted weight (TW and GW, respectively), gonad 

 weight (GNW), and liver weight (LW), with an accu- 

 racy of 0.1 g. Gonads were removed and fixed in 10% 



Seasonality of gonad development 



Monthly changes in the five following variables were 

 analyzed to determine the spawning season of blacktail 

 comber (Garcia-Diaz et al., 1997): 



1 Percent frequency of the maturity stages; this indi- 

 cates population changes in gonad development. 



2 Gonadosomatic index (GSI=(gonad weight /gutted 

 weight)xlQO): this shows differences in development 

 of the gonads with respect to gutted body weight; 



