162 



Fishery Bullelm 104(2) 



al., 1985; Yoneda et al., 2001). Samples were filtered 

 through a 100-mm mesh sieve (approximately the mini- 

 mum diameter of vitellogenic oocytes, Garcia-Diaz et 

 al., 2002) and were carefully washed under running 

 distilled water to eliminate tissue remains and fixer. 

 We used a sieve made from a piece of nylon plankton 

 net inserted between two sections of PVC pipe, 15 cm 

 in diameter and 10 cm in depth (Lowerre-Barbieri and 

 Barbieri, 1993). A compact mass of oocytes was dried 

 for 24 hours on filter paper and weighed precisely to 

 0.001 g. Afterwards, a subsample of 0.2 g was selected 

 and placed in the count dish, covered with 3-4 drops 

 of glycerin, and the number of oocytes in the sample 

 was tallied with a hand counter. Batch fecundity was 

 considered to be the total number of oocytes within 

 the most developed modal group of oocytes (Hunter et 

 al., 1985). 



Spawning frequency (the number of spawnings per 

 year by an individual) was estimated by dividing the 

 duration of the spawning season by the average number 

 of days between spawning for all individuals (Hunter 

 and Macewicz, 1985a). The duration of the spawning 

 season was the number of days between the first (7"^ 

 February) and last (16''^ July) occurrence of hydrated 

 oocyte or postovulatory follicles. The average number of 

 days between spawning was the inverse of the percent 

 frequency of hydrated individuals, multiplied by 100 

 (Collins et al., 1998). 



The potential annual fecundity estimates (PAFEs) 

 were obtained by multiplying batch fecundity by spawn- 

 ing frequency, and relative fecundity was defined as 

 PAFE divided by individual weight (Hunter et al., 

 1992). The relationships between PAFE and TL, PAFE 

 and TW, and PAFE and gonad weight (GW) were calcu- 

 lated by the following compound equation; 



where X = TL, TW, or GW; and 



a and h = specific parameters. 



A logarithmic transformation was applied to the equa- 

 tion to calculate parameters a and b by using linear 

 regression (Zar, 1996). 



Results 



Spawning season and maturity sizes 



The specimens revealed the presence of maturing and 

 ripe individuals between December and October, exclud- 

 ing January because only one individual was sampled 

 then. This finding may indicate that the population 

 spawns throughout this period, peaking between Febru- 

 ary (37.5'7f ) and June (89.8%) (Fig. 2). 



The highest values for GSI (Fig. 3A) occurred between 

 March (2.06) and July (3.37) and a peak of maximum 

 activity occurred in June (3.93), decreasing over the 

 following months. The HSI (Fig. 3B) and Kn (Fig. 3C) 

 presented irregular values during the annual cycle. 

 Consequently, no correlation was observed between 

 either ovarian and liver growth with ovarian and fish 

 growth. Oocyte diameter (DO) (Fig. 3D) values varied 

 similarly to those from the GSI; highest values occurred 

 from March (261.37 .iim) to July (275.07 ^<m) and peaked 

 in June (365.85 fim). However, the variability of oocyte 

 diameter showed the presence of mature individuals 

 (MS III + IV) in the months of September, October, and 

 December, according to gonad classification. 



The smallest individual with mature gonads was 

 16 cm TL. The maturity curve established a TLgg,; of 

 19.3 cm and TLgj;,; of 33.1 cm (Fig. 4). 



PAFE = a ib^). 



May 



I Immature I I Developing virgin or recovenng-speni | Maturing ^| Ripe wg Spent 



Figure 2 



Monthly variation (7c) in the maturity stages in the blacktnil 

 comber iSerranus atricauda). 



Reproductive potential 



From the oocyte size-frequency distributions, 

 we concluded that the type of fecundity in this 

 species is indeterminate evidenced by the lack 

 of hiatus between advanced yolked oocytes and 

 less mature oocytes (Fig. 5). 



Batch fecundity estimates (7?=28) varied 

 between 21,774 and 369,578 oocytes. These 

 estimates came from blacktail comber rang- 

 ing in total length from 22.2 to 39.8 cm. total 

 weight from 127.2 to 896.6 g, gutted weight 

 from 122.9 to 834.6 g, and gonadal weight 

 from 1.3 to 41.3 g. 



The spawning-frequency estimate for in- 

 dividuals from 17.2 to 43.2 cm TL was 42 

 times/year, and 26.5% (45/170) of individuals 

 spawned at an average of every 3.8 days. 



Potential annual fecundity estimates ranged 

 from 0.91 to 15.5 million oocytes, and an av- 

 erage of 5.1 ±4.1 million (Fig. 6). Relative 

 fecundity varied between 5062 and 20,869 

 oocytes per gram of individual, and mean 

 relative fecundity was 10,547 ±4148 oocytes. 



