Distribution of ommastrephid paralarvae in the eastern tropical Pacific

Jumbo squid (Dosidicus gigas) and purpleback squid (Sthenoteuthis oualaniensis) (Teuthida: Ommastrephidae) are thought to spawn in the eastern tropical Pacific. We used 10 years of plankton tow and oceanographic data collected in this region to examine the reproductive habits of these 2 ecologically important squid. Paralarvae of jumbo squid and purpleback squid were found in 781 of 1438 plankton samples from surface and oblique tows conducted by the Southwest Fisheries Science Center (NOAA) in the eastern tropical Pacific over the 8-year period of 1998–2006. Paralarvae were far more abundant in surface tows (maximum: 1588 individuals) than in oblique tows (maximum: 64 individuals). A generalized linear model analysis revealed sea-surface temperature as the strongest environmental predictor of paralarval presence in both surface and oblique tows; the likelihood of paralarval presence increases with increasing temperature. We used molecular techniques to identify paralarvae from 37 oblique tows to species level and found that the purpleback squid was more abundant than the jumbo squid (81 versus 16 individuals).

Reproductive potential of Yellowfin Tuna (Thunnus albacares) in the western Indian Ocean

The reproductive biology of Yellowfin Tuna (Thunnus albacares) in the western Indian Ocean was investigated from samples collected in 2009 and 2010. In our study, 1012 female Yellowfin Tuna were sampled: 320 fish on board a purse seiner and 692 fish at a Seychelles cannery. We assessed the main biological parameters that describe reproductive potential: maturity, spawning seasonality, fish condition, and fecundity. The length at which 50% of the female Yellowfin Tuna population matures (L50) was estimated at 75 cm in fork length (FL) when the maturity threshold was established at the cortical alveolar stage of oocyte development. To enable comparison with previous studies, L50 also was estimated with maturity set at the vitellogenic stage of oocyte development; this assessment resulted in a higher value of L50 at 102 cm FL. The main spawning season, during which asynchrony in reproductive timing among sizes was observed, was November–February and a second peak occurred in June. Smaller females (<100 cm FL) had shorter spawning periods (December to February) than those (November to February and June) of large individuals, and signs of skip-spawning periods were observed among small females. The Yellowfin Tuna followed a “capital-income” breeder strategy during ovarian development, by mobilizing accumulated energy while using incoming energy from feeding. The mean batch fecundity for females 79–147 cm FL was estimated at 3.1 million oocytes, and the mean relative batch fecundity was 74.4 oocytes per gram of gonad-free weight. Our results, obtained with techniques defined more precisely than techniques used in previous studies in this region, provide an improved understanding of the reproductive cycle of Yellowfin Tuna in the western Indian Ocean.

Reproductive biology of Black Anglerfish (Lophius budegassa) in the northwestern Mediterranean Sea

Gonadal morphology and reproductive biology of the Black Anglerfish (Lophius budegassa) were studied by examining 4410 specimens collected between June 2007 and December 2010 in the northwestern Mediterranean Sea. Ovaries and testes presented traits common among fishes of the order Lophiiformes. Spawning occurred between November and March. Size at first maturity (L50) was 33.4 cm in total length (TL) for males and 48.2 cm TL for females. Black Anglerfish is a total spawner with group-synchronous oocyte development and determinate fecundity. Fecundity values ranged from 87,569 to 398,986 oocytes, and mean potential fecundity was estimated at 78,929 (standard error of the mean [SE] 13,648) oocytes per kilogram of mature female. This study provides the first description of the presence of 2–3 eggs sharing the same chamber and a semicystic type of spermatogenesis for Black Anglerfish. This new information allows for a better understanding of Black Anglerfish reproduction—knowledge that will be useful for the assessment and management of this species.

An atlas of reproductive development in rockfishes, genus Sebastes

The genus Sebastes consists of over 100 fish species, all of which are viviparous and long-lived. Previous studies have presented schemes on the reproductive biology of a single targeted species of the genus Sebastes, but all appear to possess a similar reproductive biology as evidenced by this and other studies. This atlas stages major events during spermatogenesis, oogenesis, and embryogenesis, including atresia, in six species of Sebastes (S. alutus, S. elongatus, S. helvomaculatus, S. polyspinis, S. proriger, and S. zacentrus). Our study suggests that the male reproductive cycle of Sebastes is characterized by 11 phases of testicular development, with 10 stages of sperm development and 1 stage of spermatozoa atresia. Ovarian development was divided into 12 phases, with 10 stages of oocyte development, 1 stage of embryonic development, and 1 stage of oocyte atresia. Embryonic development up to parturition was divided into 33 stages following the research of Yamada and Kusakari (1991). Reproductive development of all six species examined followed the developmental classifications listed above which may apply to all species of Sebastes regardless of the number of broods produced annually. Multiple brooders vary in that not all ova are fertilized and progress to embryos; a proportion of ova are arrested at the pre-vitellogenic stage. Reproductive stage examples shown in this atlas use S. elongates for spermatic development, S. proriger for oocyte development, and S. alutus for embryological development, because opportunistic sampling only permitted complete analysis of each respective developmental phase for those species. The results of this study and the proposed reproductive phases complement the recommended scheme submitted by Brown-Peterson et al. (2011), who call for a standardization of terminology for describing reproductive development of fishes.

Reproductive dynamics of female spotted seatrout (Cynoscion nebulosus) in South Carolina

We describe reproductive dynamics of female spotted seatrout (Cynoscion nebulosus) in South Carolina (SC). Batch fecundity (BF), spawning frequency (SF), relative fecundity (RF), and annual fecundity (AF) for age classes 1−3 were estimated during the spawning seasons of 1998, 1999, and 2000. Based on histological evidence, spawning of spotted seatrout in SC was determined to take place from late April through early September. Size at first maturity was 248 mm total length (TL); 50% and 100% maturity occurred at 268 mm and 301 mm TL, respectively. Batch fecundity estimates from counts of oocytes in final maturation varied significantly among year classes. One-year-old spotted seatrout spawned an average of 145,452 oocytes per batch, whereas fish aged 2 and 3 had a mean BF of 291,123 and 529,976 oocytes, respectively. We determined monthly SF from the inverse of the proportion of ovaries with postovulatory follicles (POF) less than 24 hours old among mature and developing females. Overall, spotted seatrout spawned every 4.4 days, an average of 28 times during the season. A chronology of POF atresia for water temperature >25°C is presented. Length, weight (ovary-free), and age explained 67%, 65%, and 58% of the variability in BF, respectively. Neither RF (number of oocytes/g ovary-free weight) nor oocyte diameter varied significantly with age. However, RF was significantly greater and oocyte diameter was smaller at the end of the spawning season. Annual fecundity estimates were approximately 3.2, 9.5, and 17.6 million oocytes for each age class, respectively. Spotted seatrout ages 1−3 contributed an average of 29%, 39%, and 21% to the overall reproductive effort according to the relative abundance of each age class. Ages 4 and 5 contributed 7% and 4%, respectively, according to predicted AF values.