Food habits of Lutjanus peru (Pisces:Lutjanidae) in the coasts of Guerrero, Mexico

In this paper we describe the feeding habits of the Red snapper (Lutjanus peru) in the southern coast of Guerrero state, Mexico. This data could be relevant to local fisheries management. In total 385 full stomachs (206 from females and 179 from males) were collected monthly in 1993 and 1994, from commercial catches. Stomach contents were identified to species level when possible. Food items were grouped into taxonomically coherent groups, and their numbers, weight and frequency of occurrence obtained. The index of relative importance (IRI) was calculated for the total sample, by month, sex and size class. In 1993, a total of 42 different food items were obtained, and 43 in 1994. Food items consisted of fishes, crustaceans, and mollusks. The grouping of prey species, genera, or families rendered 14 food groups, as follows: Mollusks, Amphipods, Copepods, Stomatopods, Penaeus vannamei, Brachiuran Larvae, Stomatopods Larvae, Family Albuneidae Larvae, Other crustaceans, Anchoa ischana, Anchoa lucida, Other fishes, Salps and Unidentified organic matter. Anchoa ischana dominated the trophic spectrum in both years. Although, Amphipods, Anchoa lucida and Other fishes had important indexes in 1994. There was high variability in the diet composition by month. Nevertheless, in 1993, from February to August, crustaceans as a whole dominated the diet. In 1994, crustaceans only dominated in March and August. No differences in food habits were found between immature fish, males and females. The diet of the Red snapper varies as they grow, although the same food groups are found always. At the adult phase, in length classes over 261 mm FL, there is some degree of specialization, as they consume more fish, particularly engraulids.     

Reproductive aspects of the yellowtail snapper Ocyurus chrysurus from the southern Gulf of Mexico

In this study, sex ratio, spawning season, fork length (L(F)) at maturity (L(F50)), batch fecundity and spawning frequency were characterized for the continental population of Ocyurus chrysurus from the Campeche Bank, in the southern Gulf of Mexico. A total of 1657 specimens were collected from February 2008 to January 2009. The overall sex ratio (male:female) and sex ratios by size-class showed no significant differences from an expected 1:1 ratio. The Campeche Bank population did not conform to the reproductive seasonality pattern characteristic of a continental population. A protracted spawning season that extended from January to September with peaks occurring mainly between April and May and additionally in September was observed. The population conformed, however, to the sexual maturity pattern observed for populations and species associated with a continental margin. Fish of both sexes reached the onset of sexual maturity at a similar and small L(F) of c. 14 cm, and L(F50) (L(F) at which 50% of females and males become mature) was 21·3 and 19·4 cm. Asynchronous-type ovarian development was observed for this species and batch fecundity estimates ranged from 14,102 to 164,756 oocytes (mean ±S.D. = 43,852 ± 32,684 oocytes). The overall spawning frequency estimate was once every 8·3 days or 26 times during the 9 month spawning season.     

Interannual variations in condition indices of larval Norwegian spring-spawning herring

The sea water temperature off the Norwegian coast was lower in 1994 than in 1992 and 1993. RNA/DNA ratios of Norwegian spring spawning herring increased with increasing larval dry weight all years, except for larvae sampled south of 62°N in 1994. The RNA/DNA ratios indicated that each year, only a small portion ( 0.7%) of the larvae were starving. RNA/DNA ratios and temperature were negatively correlated in 1992, but in other years no significant correlations were found. Residuals of In RNA v . In DNA and In W v. L _s were poorly correlated in all years, but residuals of In RNA v. In DNA and In DNA v. In W were negatively correlated in all years. Principal component analysis showed that the RNA/DNA ratio and DNA (% of weight) were correlated with different axes. Abundance data for herring at the early larval and 0-group stages in 1992–1994 indicated higher mortality in 1994 compared with the other years. The data do not indicate that average larval condition was poorer in 1994 than in other years. However, the variability in larval condition was higher in 1994 than in other years, and the condition of later larval stages was relatively lower in 1994 than in other years.     

Temporal changes in the relationship between observed and expected sex-investment frequencies, social structure and intraspecific parasitism in Leptothorax tuberum (Formicidae)

The proportional investment in females (IF0) was observed in three Dorset (UK) populations (Portland, Holworth and St Alban's Head) of the ant Leptothorax tuberum during 1993 and 1994. The workers' optimum investment in females predicted by kin selection theory (IF_E) was calculated for these populations from relatedness values estimated from an isozyme polymorphism. Although a previous study at Portland in 1992 found IF_o and IF_E not to differ, in 1993 IF_o and IFE were significandy different from each other at Portland and St Alban's Head. In 1994 the difference was significant at Portland only. IF_o was lower than IF_E at all three sites in both years. The differences between 1992 and 1993 and 1994 were consistent with either an unresolved conflict between workers and queens for control of the IF or change in an environmental factor that affected all sites. Relatedness values showed that at Portland most nests were founded by one singly-mated queen. However, at St Alban's Head relatedness values were consistent with some serial polygyny in 1993 but not 1994, while at Holworth there was some egg-dumping by queens unrelated to the colony queen. The differences in nest structure between sites may have been related to habitat differences. In 1993 there was evidence of a split sex ratio. However, unlike 1992, the female biased nests did not have a higher relatedness asymmetry than the male biased nests.     

Effects of different photoperiods and handling stress on spawning and reproductive performance of pikeperch Sander lucioperca

The objective of this study was to control the reproductive cycle of pikeperch (Sander lucioperca) through determining the effects of different photoperiods and handling stress on the reproduction quality, timing and quality of spawning, fertilization, sex steroids, and cortisol concentrations. In this study, 72 pikeperch broodstocks with an average weight of 1367 ± 55.3 g were exposed to different photoperiods including constant light (24L:0D), constant darkness (0L:24D), and 12 h of light, 12 h of darkness (12L:12D) for 40 days. Half of the broodstocks of each photoperiod treatment were exposed to handling stress at a specific time of the day. Applying different photoperiods caused changes in the timing of broodstocks' spawning, so that fish under 24L:0D spawned earlier than those of other photoperiods, and stressed fish of the 0L:24D photoperiod had a delayed spawning compared to others. Also, the spawning of the broodstocks at different photoperiods which were exposed to handling stress was either delayed or did not occur at all. The highest and lowest spawnings were observed in the morning and at night, respectively. Fertilization percentage, number of eggs per gram, sex steroids including estradiol, progesterone, and testosterone, as well as cortisol and calcium concentrations did not show any significant difference in different photoperiods and handling stress. In stressed males of the 24L:0D photoperiod, there only was a significant decrease of testosterone concentration compared to the beginning of the experiment. Results indicated that the spawning performance of pikeperch broodstocks could be considerably stimulated using an effective photoperiod. Similarly, pikeperch broodstocks in culture systems are usually affected by handling stress, and this stress could lead to a poor reproductive performance and inhibition of spawning.     

Difference on reproductive trait of skipjack tuna <Emphasis Type="Italic">Katsuonus pelamis</Emphasis> female between schools (free vs FAD school) in the tropical western and central Pacific Ocean

In order to clarify the difference on reproductive traits of female skipjack tuna between fish aggregation device (FAD) and free-swimming (Free) school, we examined the relative condition factor and sex ratio, minimum size at first maturity and spawning fraction in tropical western and central Pacific Ocean. The relative condition factor in developing (FAD: 1.00 ± 0.06, Free: 1.05 ± 0.07) and spawning capable phase (FAD: 1.01 ± 0.06, Free: 1.04 ± 0.06) was higher in the free-swimming school than those in the fish aggregation device school (p < 0.01). The proportion of mature fish was significant difference between each schools (p < 0.05). The sex ratios in the schools were not biased (p > 0.05). Observed minimum size at first maturity were 40.0 cm FL in FAD and 42.5 cm FL in free-swimming school. Spawning capable fish were observed year around in FAD and for seven months in free-swimming school. The estimated total spawning fractions based on the postovulatory follicle method were 0.50 and 0.49 in the FAD and free-swimming schools, respectively. These results suggested that differences in the school type did not affect inherent spawning characteristics (i.e. sex ratio, minimum size at first maturity, or spawning season) and may shortly affect the oogenesis throughout the food availability.     

Reproductive biology and implications for management of the spangled emperor Lethrinus nebulosus in the southern Arabian Gulf

The reproductive biology of the spangled emperor Lethrinus nebulosus in the southern Arabian Gulf was determined from the examination of 781 individuals collected between September 2008 and August 2009. There was no histological evidence of adult sex change, and sex ratios did not differ significantly from unity across all size and age classes. Testes had an ovarian structure and a remnant lumen which was not used for sperm transport; furthermore, residual oocytes were observed in the testes of some immature, resting and developing males. A dramatic change in the sex ratio of the smallest and youngest size and age classes suggested that juvenile female to male sex change occurred between 21·0 cm fork length (L(F)) and 24·0 cm L(F) at 1 year of age. The combination of histological evidence with the sexual composition of the size and age structures suggests a non-functional protogynous hermaphroditic sexual pattern, which is analogous to functional gonochorism. The spawning season was well defined, occurring once a year during March, April and early May. Peaks in spawning occurred after full moons, there was a cessation in spawning activity after new moons and spawning was completed within three lunar cycles. The distribution of males over the entire size and age ranges and the absence of inactive mature females during the spawning season suggested that the population was not constrained by sperm limitation. Size-specific and age-specific reproductive potential indicated that conventional regulations that equate the mean size at first capture to sexual maturation are unsuitable for the management of L. nebulosus. The maximum recorded age (11 years), small mean size and young age at sexual maturation (L(m50) = 26·7 cm L(F), 2·1 years, for females and 19·4 cm L(F), 0·5 years, for males) may be a direct result of intensive demersal fishing in the southern Arabian Gulf.     

Spawning population characteristics of pike <Emphasis Type="Italic">Esox lucius</Emphasis> L. in Lake Rubikiai (Lithuania)

The aim of the study was to describe the peculiarities of pike spawning in mesotrophic Lake Rubikiai, to determine the spawning population structure and evaluate the influence of some environmental factors on year-class strength formation. The data were collected in April and May (1994–2011). A total of 1586 individuals were caught. The age of pike ranged from 1 to 12 years; 2–5-yearold males (96.0%) and 3–8-year-old females (89.1%) prevailed. The overall sex ratio of females to males was 1:4.1. One-year-old spawning males (26.5–28.5 cm) and two-year-old spawning females (31.5–35.5 cm) constituted 2.1% and 2.6%, respectively. Water temperature during the spawning period was relatively stable, between 4 and 6°C, during March and increased slightly towards 10°C in the middle of April. No correlation was observed between female length and spawning date. Year-class strength did not correlate with the last day of ice presence and the minimal water level at the end of spawning (WL_min), but statistically significantly negatively correlated with the maximum water level at the beginning of spawning (WL_max) and the difference between WL_max and WL_min. The mean annual survival rate for pike (aged ≥2) was 0.74 and the mean annual instantaneous mortality rate was 0.45.     

Reproductive biology of Astyanax fasciatus (Pisces: Characiformes) in a reservoir in southeastern Brazil

To study the reproductive biology of Astyanax fasciatus (Cuvier, 1819) in Furnas Reservoir, Minas Gerais, Brazil, a total of 1307 specimens were captured in bimonthly sampling from August 1993 to July 1994. The sex ratio showed a predominance of females, representing 65.2% of the total sample. The stages of gonadal maturation and spawning type were determined through macro- and microscopic analysis of the gonads as well as by variation in the gonadosomatic indices. A . fasciatus showed fractionated spawning and reproduction throughout the year, with spawning peaks influenced by water temperature and rainfall. Males and females initiated gonadal maturation at a mean standard length of 6.4 and 6.5 cm, respectively. During gonadal maturation, females showed a reduction in hepatosomatic index (from 1.06 to 0.83), suggesting that hepatic substances are transferred from the liver to the ovaries. In the reproductive period, A. fasciatus had lower stomach repletion and coelomic fat indices, indicating that this species ate less and consumed more fat reserves when reproduction had the maximum GSI (11.3 for females and 2.7 for males). Weight of the ovaries had a positive influence on the condition factor (K1), as the lowest K2 value (weight without gonads) were obtained during maturation, confirming the influence of the ovaries upon the physiological condition of the females. In weight–length relationship, parameter b was 3.02 for females and 2.23 for males, and the correlation coefficient ( r ²) was 0.84 and 0.66, respectively.     

Return migration of Atlantic Salmon in the River Tana: Phases of migratory behaviour

From a total of 174 multi-sea-winter Atlantic salmon radio tagged in the Tanafjord (northern Norway, 70°N) during 1992 and 1993, 48 Atlantic salmon were followed from entering the River Tana until spawning. Three phases were identified: (1) migratory, direct or stepwise migration to, or close to the position held at spawning; (2) search, movements both up and down river at or close to the position held at spawning; (3) holding, a period without movements prior to spawning. During the migratory phase, Atlantic salmon migrated directly to near the spawning area, or stopped between one and nine shorter periods during the upstream migration. Number of stops increased with increasing migratory distance in 1993, but no such correlation was found in 1992. The highest migratory speeds were recorded in the lower parts of the river. A distinct change in migratory pattern was found in 67% of the Atlantic salmon near or at the area held at spawning. Most common was a search phase of erratic movements with more than one down river movement. After the movement terminated, 96% of the Atlantic salmon had a period when no or little movement was recorded until spawning (on average 55 days in 1992 and 51 days in 1993). There was no preference for staying at, up or down river from the spawning area during this holding period. Early ascending Atlantic salmon migrated to spawning areas further from the mouth than the later arriving Atlantic salmon in 1993, but not in 1992. The proportion of time spent on the migratory phase increased, while the proportion of time spent on the holding phase decreased with increasing distance to the spawning area.     

Reproductive biology of Sarotherodon mossambicus (Cichlidae) in Plover Cove Reservoir,Hong Kong

Synopsis A 16-month study (August 1972 to November 1973) of Sarotherodon mossambicus in the Plover Cove Reservoir, Hong Kong revealed a sex ratio of 1:1 for small fish (below 19 cm standard length), but above this length males predominated in the population. Monthly sex composition also showed this approximately 1:1 ratio except during the months of August and September, when again males predominated. Males and females reached M₅₀ at an average length of 17.8 cm and 16.2 cm respectively. Maturity and gonosomatic index studies showed that spawning occurred from May to October with peaks in June and August, and there were at least two spawnings each year. The relationship between fecundity and standard length of females collected during both spawnings was computed to be F = 118.49L–1150.91.     

Comparative efficacy of two controlled-release gypsy moth mating disruption formulations

The effects of aerial applications of the gypsy moth sex pheromone, disparlure, on mating disruption and suppression of growth of populations of the gypsy moth, Lymantria dispar (L.), were investigated. Two formulations of disparlure, plastic laminate flakes applied in a single application and polymethacrylate beads applied in two applications, were compared in two separate tests conducted in 1993 and 1994. The beads were applied in two applications spaced 2 weeks apart because preliminary tests had indicated that they released pheromone too rapidly to maintain adequate emission rates throughout the period of male flight. In 1993, the flakes were applied at a rate of 50 g a.i./ha, and the beads were applied at a rate of 15 g a.i./ha for each application. In 1994, the flakes were applied at a rate of 75 g a.i./ha and the beads were applied at rates of 32.5 and 42.5 g a.i./ha for the two applications. Beads with larger average particle size were used in 1994 to prolong disparlure release. The treatments applied in 1993 resulted in >97% reduction in mating and >82% suppression of population growth in the following year. Because of a 1995 collapse of gypsy moth populations in the vicinity of the tests, reliable population growth data were not available for the treatments applied in 1994, but significant mating disruption did occur under both treatments. Based on measurements of residual disparlure after field aging, the flakes released 32 and 48% of their disparlure content during the 6 weeks of male moth flight in 1993 and 1994, respectively. The smaller beads used in 1993 released 75% of their disparlure content, and the larger beads used in 1994 released 52% of their disparlure content, during the 6 weeks of male flight. The biological efficacy data suggest that the bead and flake formulations, as applied in these tests, have similar effects on gypsy moth mating disruption and subsequent population growth. Based on the observed release rates from both 1993 and 1994, a single application of the beads would provide emission rates equal to or greater than those provided by the flakes when applied at an equal dose.     

Reproductive life history of the introduced peacock grouper Cephalopholis argus in Hawaii

This research investigated the reproductive biology (sex ratio, hermaphroditic pattern, size and age at maturity) of Cephalopholis argus, known locally in Hawaii by its Tahitian name roi. The results suggest that C. argus exhibits monandric protogyny (female gonad differentiation with female to male sex change) with females reaching sexual maturity at 1.2 years (95% c.i .: 0.6, 1.6) and 20.0 cm total length (L_T; 95% c.i .: 19.6, 21.2). The female to male sex ratio was 3.9:1. The average age and L_T at sex change was 11.5 years (95% c.i .: 11.1, 12.9) and 39.9 cm (95% c.i .: 39.5, 41.2), respectively. Current information on spawning seasonality of this species is incomplete, but based on the occurrence of spawning capable and actively spawning females, spawning probably takes place from May to October. Evidence of lunar spawning periodicity was found, with an increased proportion of spawning capable and actively spawning females, and an increased female gonado‐somatic index during first quarter and full‐moon phases. This information fills a valuable information gap in Hawaii and across the species' native range.     

Effects of different photoperiods on the reproduction of the barbel, Barbus barbus (L.), reared at constant temperature

The role of photoperiod as an environmental factor controlling reproduction, particularly the duration and ending of the breeding season, in the barbel was investigated by tank experiments. The experiments used a population of barbel matured in captivity which were stripped of eggs at frequent intervals: 10–15 'spawnings'for each female were obtained at 15-day intervals.
A decreasing photoperiod (16·5 light: 7·5 dark→8L: 16D), for an annual cycle contracted to 6 months duration, inhibited the spawning of both female and male fish. This allowed two periods of reproduction (February-May and September-November) within one year. Under natural or constant (10L: 14D) photoperiod conditions, spawning came to an end spontaneously. The rate (accelerated, slow or natural) of daylength increase did not affect the onset of spawning.     

Reproductive and sexual characteristics in five Lethrinus species in waters off the Ryukyu Islands

Gonads of five lethrinids, viz., Lethrinus harak, L. miniatus, L. obsoletus, L. ornatus, and L. sp. 2, were collected monthly in waters off the Ryukyu Islands and observed histologically to reveal their spawning periods and size at sexual maturation and sexual transition. The spawning period was from April to November for L. harak, from April to July for L. miniatus, from April to October for L. obsoletus, from May to November for L. ornatus, and from April to October for L. sp. 2. Sexual patterns in the five species were determined by fork length at both sexual maturation and sexual transition. The body size (fork length, FL) and sex ratio (% of female) at 90% maturity in L. harak were 21.1 cm FL and 90%, respectively; those of L. miniatus were 42.2 cm FL and 80%; 25.7 cm FL and 60% for L. obsoletus; about 20 cm FL and 90% for L. ornatus; and about 26 cm FL and 90% for L. sp. 2. Because the sex ratios decreased to 0% at the maximum size classes in L. miniatus, L. ornatus, and L. sp. 2, the sexual patterns in these species were considered to be protogynous hermaphrodite. Although the sex ratio (% of female) once decreased to about 30% at 28 cm FL, rapid increase occurred in the larger size class in L. harak. However, the increase did not result from sexual transition. Hence, the sexual pattern of L. harak was considered to be protogynous hermaphrodite. Because the sex ratio (% of female) at body sizes larger than 23 cm FL was stable at about 60% in L. obsoletus, the sexual pattern was determined to be one of juvenile hermaphrodites.     

Selection-induced variation at the pantophysin locus (PanI) in a Norwegian fjord population of cod (Gadus morhua L.)

A total of 1290 cod (Gadus morhua L.), sampled between 1985 and 1999 from a spawning area in the Trondheimsfjord, Norway, were assayed for the nuclear-encoded locus PanI (pantophysin). The majority of samples were taken during the spawning season at two nearby sampling locations at depths of 100 and 60 m, respectively. Genetic analysis revealed significant effects of cohort, sex and sampling location on allele frequencies at PanI. The contribution of each of these three factors to the total among-sample diversity (FST) of 8.01% at PanI was estimated to be 3.78, 2.55 and 1.68%, respectively. Sign tests revealed a significant excess of heterozygotes at both sampling locations in females; a significant excess of heterozygotes in males was observed at one of the localities. Mutation, genetic drift and immigration do not appear to contribute significantly to the observed genetic heterogeneity at PanI, leaving natural selection as the main explanatory factor for the Hardy-Weinberg imbalance. The dynamics of the selection at PanI appear to be complex. Analysis of age, sex and cohort proved crucial to disentangle putative explanatory factors from their secondary effects.     

Ovarian atresia and sex ratio imbalance in white sucker, Catostomus commersoni

In a small north-temperate lake, 53–56% of post-spawning, female white suckers spanning a wide range of ages showed ovarian atresia in 1981 and 1987. Comparison of ovarian atresia frequencies and adult sex ratios in nine white sucker populations indicated that this spawning disorder may have been due to a paucity of males at spawning. Adult female:male sex ratio in the King Lake population was 2.82:1 in 1981 and 2.73:1 in 1987, compared with 0.91:1 to 1.75:1 in populations that exhibited lower resorption frequencies (0–7.1%). Removal of 29% of the King Lake male suckers in 1988 elevated the female: male sex ratio to 3.5:1 and frequency of ovarian atresia rose to 75%. Unspawned ova were almost completely resorbed 3 months after the spring spawning period. Post-spawning mortality was not different between spent and resorbing females. The somatic condition of resorbing and spent females did not differ. There was no evidence that atresia interfered with gamete development subsequently. The sex ratio imbalance present in King Lake was not a function of population density.     

Seasonal abundance and depth distribution of Blennius fluviatilis and introduced Lepomis gibbosus, in Lake Banyoles (Catalonia, Spain)

Temporal and spatial occurrence of limnetic larval fish in Lake Banyoles in the spring and summer of 1993 and 1994 indicated that pumpkinseed spawned over 15 weeks (from mid-May to mid-August) and freshwater blenny over 14 weeks (from mid-May until early August). We noted that the spawning period of pumpkinseed commenced earlier in Lake Banyoles than in more northern lakes. Pumpkinseed and freshwater blenny larvae were collected by tow net in both the limnetic (at 4–4.5 m) and littoral zones (at 0–0.5 m), during daylight (no samples were taken during night). Freshwater blenny larvae were more abundant than pumpkinseed larvae. Both of them were more abundant in 1993 than in 1994 (pumpkinseed: 1.61 ind. 100 m−3 vs. 0.70 ind. 100 m−3; freshwater blenny: 3.95 ind. 100 m−3 vs. 1.90 ind. 100 m−3) and in both years they were uniformly distributed in the lake, without differences between the areas considered. The pumpkinseed larvae migrated at 3.5 mm TL into the limnetic zone, and returned to the vegetation of the littoral zone as juveniles. The freshwater blenny larvae were also planktonic (3.5–14 mm TL) but were distributed in both the littoral and limnetic zone before benthic settlement. The larval distribution is discussed on the basis of a trade-off between foraging and predation risk. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lake Erie sport and boat show patrons rank Great Lakes ecosystem health issues in 1993 and 1994

In 1993 and 1994 patrons of the Mid-America Boat Show and the American-Canadian Sport, Travel and Outdoor Show, both held in Cleveland, Ohio were asked to respond to an Ohio Sea Grant survey on Great Lakes issues. In 1993 and 1994, a list of issues, identified from previous surveys and citizen advisory groups, were presented to show patrons at the Ohio Sea Grant exhibit. They were asked to rank the importance of each issue on a scale of 0 to 6. A total of 1,751 and 987 boat show and sport show patrons responded in 1993 and 1994 respectively. The four highest ranked issues and their arithmetic means and standard deviations in 1993 and 1994 respectively, were: Lake Erie water quality (5.60±0.79 and 5.53±0.81); Eliminating persistent toxic substances in the Great Lakes (5.54±0.88 and 5.49±0.89); Protecting the Great Lakes ecosystem (5.49±0.87 and 5.51±0.80); and Toxic contaminants in fish (5.49±0.97 and 5.36±1.00). A t-test was used to compare means of 1993 and 1994 responses. Significant differences (0.05) occurred in mean responses for 9 out of 14 issues common to both the surveys. Factor analysis of 1993 data suggested that patrons of the 1993 shows: (1) have a strong concern for the Great Lakes ecosystem; and (2) recognize that individual actions count. Factor analysis of the 1994 data indicated that show patrons continued to have a concern for the Great Lakes ecosystem. Boat and outdoor show patrons (recreational resource users) are a constituency that can, if politically active, validate and support efforts to protect and preserve the Great Lakes ecosystem.     

A comparison of the maturation and growth of female flathead sole in the central Gulf of Alaska and south‐eastern Bering Sea

Female flathead sole Hippoglossoides elassodon maturity appears not to be area dependent since the total length ( L _T) at which 50% were mature ( L _T50) was similar for the central Gulf of Alaska (333 mm) and south‐eastern Bering Sea (320 mm) areas. Likewise the age at which 50% were mature ( A ₅₀) was similar in the south‐eastern Bering Sea (9·7 years) and central Gulf of Alaska (8·7 years). The timing of female flathead sole spawning may also be similar between areas. Batch or serial spawning was indicated for flathead sole. Female flathead sole grew at a similar rate in both the Gulf of Alaska and Bering Sea. In contrast, males grew faster in the Bering Sea than in the Gulf of Alaska. Males grew more slowly than females in both areas after 5 years of age, and reached a smaller maximum L _T. The growth of both sexes was similar during 1993 and 1996 in the Gulf of Alaska.