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Intra-and interannual variability of fecundity and egg size of lumpfish (Cyclopterus lumpus) were assessed for 2009 and for 2014-2019 and compared with fecundity estimates from 1967 and 1969. Downregulation of fecundity was apparent throughout ovary development, but the intensity was reduced close to spawning. The fecundity of fish spawning later in the year was higher than that of fish that spawned earlier. Carcass weight was a better predictor of fecundity than length. The model was improved through the addition of liver weight, but this led to an increase of <1.0% in the explained variance in fecundity. Variation in fecundity between the periods studied (2009 and 2014-2019) was low; however, fecundity in these study periods was higher than in 1967 and lower than in 1969. Whether these differences were due to differences in methods could not be ruled out. Average egg diameter was positively correlated with fish size and decreased from the first to the second batch, and only limited variation between years was observed in this characteristic. [ABSTRACT FROM AUTHOR]

Features of oogenesis, ovarian maturity phases and fecundity of the smooth lumpsucker (Aptocyclus ventricosus) are described here for the first time. Gonadal development was examined by histological methods and the morphological features and size of germ cells at various stages was determined. These features were used to more accurately define morphological criteria of 7 histological and macroscopic maturity phases. The smooth lumpsucker is an iteroparous gonochoristic species with determinate fecundity, group-synchronous ovary organization, total spawning (release of 1 batch of eggs per breeding season), and external fertilization. [ABSTRACT FROM AUTHOR]

Accurate maturity-at-age data are necessary for estimating spawning stock biomass and setting reference points for fishing. This study is the first on age at maturity of female sablefish (Anoplopoma fimbria) sampled in Alaska during their winter spawning period, when maturity is most easily assessed. Skipped spawning, the situation where fish that have spawned in the past do not spawn during the current season, was documented in female sablefish for the first time. Determination of age at maturity was heavily influenced by whether these fish that would skip spawning were classified as mature or immature; age at 50% maturity was 6.8 years when fish that would skip spawning were classified as mature, and 9.9 years when classified as immature. Skipped spawning was more common on the continental shelf, and rates of skipped spawning increased with age through age 15. Estimates of age at maturity were similar for samples collected in winter and summer, when fish that would skip spawning sampled during winter were classified as mature. When fish that would skip spawning were considered immature in the sablefish population model for Alaska, estimates of spawning biomass decreased. Relative fecundity did not change with size and age, verifying the assumption made in the Alaska sablefish stock assessment that relative reproductive output is linearly related to female spawning biomass. [ABSTRACT FROM AUTHOR]

Southern Kingfish (Menticirrhus americanus) is an abundant sciaenid in the northcentral Gulf of Mexico, but little is known of its life history. Our objectives were to describe demographic traits and compare the characteristics of this population with those of other recreationally and commercially important populations in the U.S. Exclusive Economic Zone (U.S. EEZ). We report significant differences in sex-specific weight at length. Otolith annulus formation occurred in April and May and maximum age was 4+ years for both sexes. Length-at-age analysis indicated that mean asymptotic total length (TL; TL∞, male=244 mm, TL∞, female=303 mm) and mean instantaneous growth rates (kmale=1.12 y-1 and kfemale=0.95 y-1) were significantly different between sexes. The mean length at 50% maturity (TL50) for females was 171 mm TL, corresponding to an age at maturity of 1 year. Gonadosomatic indices and histological examination of ovarian maturity phases indicated rapid gonadal development in February and March with females actively spawning from April to September. The interval between spawning averaged 6.9 days, and the most frequent spawning occurred in June and July. Mean relative batch fecundity was 231.1 number of eggs g-1 of ovary-free body weight (±standard error 35.7). Principal component analysis (PCA) of 5 variables from 17 sciaenid populations in the U.S. EEZ identified 2 principal components that explained 68.1% of variation among populations; these components represent a size-related gradient and a gradient of spawning season dynamics. Five distinct groups were identified on the basis of fish size, age at maturity, spawning-season duration, and batch fecundity. [ABSTRACT FROM AUTHOR]

The influences of age, size, and condition of spawning females on fecundity and oocyte quality were analyzed for the Patagonian stock of Argentine Hake (Merluccius hubbsi). Samples of mature females were collected in the spawning area as part of 2 research surveys conducted in January 2010 and 2011, during the peak of the reproductive season. Batch fecundity (BF) ranged between 40,500 (29 cm total length [TL]) and 2,550,000 (95 cm TL) hydrated oocytes, and was positively correlated with TL, gutted weight, age, hepatosomatic index (HSI), and the relative condition factor (Kn). Relative fecundity ranged between 85 and 1040 hydrated oocytes g-1 and showed significant positive relationships with gutted weight, HSI, and Kn; however, coefficients of determination were low for all regressions. Dry weights of samples of 100 hydrated oocytes ranged between 1.8 and 3.95 mg and were positively correlated with all variables analyzed, including batch and relative fecundity. Multiple regression models created with data of the morphophysiological characteristics of females supported maternal influences on fecundity and egg weights. Within the studied size range (29-95 cm TL), larger individuals had better somatic and egg condition, mainly revealed by higher HSI and hydrated oocytes with larger oil droplets (275.71µm [standard error 1.49]). These results were associated with the higher feeding activity of larger females during the spawning season in comparison with the feeding activity of young individuals (<5 years old); the better nutritional state of larger females, assumed to result from more feeding, was conducive to greater production of high-quality eggs. [ABSTRACT FROM AUTHOR]

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 (L5o) 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 skipspawning 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. [ABSTRACT FROM AUTHOR]

Most assessments of fish stocks use some measure of the reproductive potential of a population, such as spawning biomass. However, the correlation between spawning biomass and reproductive potential is not always strong, and it likely is weakest in the tropics and subtropics, where species tend to exhibit indeterminate fecundity and release eggs in batches over a protracted spawning season. In such cases, computing annual reproductive output requires estimates of batch fecundity and the annual number of batches-the latter subject to spawning frequency and duration of spawning season. Batch fecundity is commonly measured by age (or size), but these other variables are not. Without the relevant data, the annual number of batches is assumed to be invariant across age. We reviewed the literature and found that this default assumption lacks empirical support because both spawning duration and spawning frequency generally increase with age or size. We demonstrate effects of this assumption on measures of reproductive value and spawning potential ratio, a metric commonly used to gauge stock status. Model applications showed substantial sensitivity to age dependence in the annual number of batches. If the annual number of batches increases with age but is incorrectly assumed to be constant, stock assessment models would tend to overestimate the biological reference points used for setting harvest rates. This study underscores the need to better understand the ageor size-dependent contrast in the annual number of batches, and we conclude that, for species without evidence to support invariance, the default assumption should be replaced with one that accounts for ageor size-dependence. [ABSTRACT FROM AUTHOR]

The long-snouted seahorse (Hippocampus guttulatus) (Cuvier, 1829), was used to validate the predictive accuracy of three progressively realistic models for estimating the realized annual fecundity of asynchronous, indeterminate, multiple spawners. Underwater surveys and catch data were used to estimate the duration of the reproductive season, female spawning frequency, male brooding frequency, and batch fecundity. The most realistic model, a generalization of the spawning fraction method, produced unbiased estimates of male brooding frequency (mean ±standard deviation [SD]=4.2 ±1.6 broods/year). Mean batch fecundity and realized annual fecundity were 213.9 (±110.9) and 903.6 (±522.4), respectively. However, females prepared significantly more clutches than the number of broods produced by males. Thus, methods that infer spawning frequency from patterns in female egg production may lead to significant overestimates of realized annual fecundity. The spawning fraction method is broadly applicable to many taxa that exhibit parental care and can be applied nondestructively to species for which conservation is a concern. [ABSTRACT FROM AUTHOR]

The article focuses on the findings of a study on the estimates of natural mortality rate, annual fecundity and maturity at length for Greenland halibut from the Bering Sea and Aleutian Islands, Alaska. U.S. National Marine Fisheries Service (NMFS) scientists gathered fish ovaries for the study. The gonadosomatic index-mortality (GSI-M) estimate used fishes with ovaries in maturity state vitellogenesis 4. All females smaller than 65 centimeters were classified as immature.

Annual potential fecundity, batch fecundity, and oocyte atresia were estimated for Atka mackerel (Pleurogrammus monopterygius) collected in Alaskan waters during 1993-94. Atka mackerel were assumed to be determinate spawners on the basis of decreasing fecundity after batch spawning events. Histological examination of the ovaries indicated that oocytes in the vitellogenic stage and higher had been spawned in the current spawning season. For an average female of 40 cm, potential annual fecundity was estimated to be 41,994 eggs, average batch size (i.e., batch fecundity) was estimated to be 6689 eggs, and there were 6.13 batches per spawning season. Atresia was estimated by examining postspawning specimens and was found to be substantial. The average amount of atresia for a 40-cm fish was estimated to be 11,329 eggs, resulting in an estimated realized fecundity of only 30,664 eggs and 4.64 batches of eggs per spawning season. [ABSTRACT FROM AUTHOR]

Blacktail comber (Serranus atricauda Günther) is a commercially important species in the Canary Islands fisheries. A total of 425 individuals were collected and histological techniques were used to investigate the reproductive data. Results indicated that the spawning season occurred throughout the year, peaking between March and July. Individuals reached 50% maturity at 19.3 cm TL and 95% at 33.1 cm TL. Batch fecundity estimates ranged from 21,774 to 369,578 oocytes per spawning event for specimens from 22.2 to 39.8 cm TL. Blacktail comber was estimated to spawn 42 times/year and 26.5% of individuals spawned, on average, every 3.8 days. Estimates of potential annual fecundity for the species ranged from 0.91 to 15.5 million oocytes, and an average of 5.1 ±4.1 million. [ABSTRACT FROM AUTHOR]

Fecundity was estimated for shortspine thornyhead (Sebastolobus alascanus) and longspine thornyhead (S. altivelis) from the northeastern Pacific Ocean. Fecundity was not significantly different between shortspine thornyhead off Alaska and the West Coast of the United States and is described by 0.0544 x FL3.978, where FL =fish fork length (cm). Fecundity was estimated for longspine thornyhead off the West Coast of the United States and is described by 0.8890 x FL3.249. Contrary to expectations for batch spawners, fecundity estimates for each species were not lower for fish collected during the spawning season compared to those collected prior to the spawning season. Stereological and gravimetric fecundity estimation techniques for shortspine thornyhead provided similar results. The stereological method enabled the estimation of fecundity for samples collected earlier in ovarian development; however it could not be used for fecundity estimation in larger fish. [ABSTRACT FROM AUTHOR]

Loligo opalescens live less than a year and die after a short spawning period before all oocytes are expended. Potential fecundity (EP), the standing stock of all oocytes just before the onset of spawning, increased with dorsal mantle length (L), where EP = 29.8L. For the average female squid (L of 129 ram), EP was 3844 oocytes. During the spawning period, no oogonia were produced; therefore the standing stock of oocytes declined as they were ovulated. This decline in oocytes was correlated with a decline in mantle condition and an increase in the size of the smallest oocyte in the ovary. Close agreement between the decline in estimated body weight and standing stock of oocytes during the spawning period indicated that maturation and spawning of eggs could largely, if not entirely, be supported by the conversion of energy reserves in tissue. Loligo opalescens, newly recruited to the spawning population, ovulated about 36% of their potential fecundity during their first spawning day and fewer ova were released in subsequent days. Loligo opalescens do not spawn all of their oocytes; a small percentage of the spawning population may live long enough to spawn 78% of their potential fecundity. Loligo opalescens are taken in a spawning grounds fishery off California, where nearly all of the catch are mature spawning adults. Thirty-three percent of the potential fecundity of L. opalescens was deposited before they were taken by the fishery (December 1998-99). This observation led to the development of a management strategy based on monitoring the escapement of eggs from the fishery. The strategy requires estimation of the fecundity realized by the average squid in the population which is a function of egg deposition and mortality rates. A model indicated that the daily total mortality rate on the spawning ground may be about 0.45 and that the average adult may live only 1.67 days after spawning begins. The rate at which eggs escape the... [ABSTRACT FROM AUTHOR]

Fisheries models have traditionally focused on patterns of growth, fecundity, and survival offish. However, reproductive rates are the outcome of a variety of interconnected factors such as life-history strategies, mating patterns, population sex ratio, social interactions, and individual fecundity and fertility. Behaviorally appropriate models are necessary to understand stock dynamics and predict the success of management strategies. Protogynous sex-changing fish present a challenge for management because size-selective fisheries can drastically reduce reproductive rates. We present a general framework using an individual-based simulation model to determine the effect of life-history pattern, sperm production, mating system, and management strategy on stock dynamics. We apply this general approach to the specific question of how size-selective fisheries that remove mainly males will impact the stock dynamics of a protogynous population with fixed sex change compared to an otherwise identical dioecious population. In this dioecious population, we kept all aspects of the stock constant except for the pattern of sex determination (i.e. whether the species changes sex or is dioecious). Protogynous stocks with fixed sex change are predicted to be very sensitive to the size-selective fishing pattern. If all male size classes are fished, protogynous populations are predicted to crash even at relatively low fishing mortality. When some male size classes escape fishing, we predict that the mean population size of sex-changing stocks will decrease proportionally less than the mean population size of dioecious species experiencing the same fishing mortality. For protogynous species, spawning-per-recruit measures that ignore fertilization rates are not good indicators of the impact of fishing on the population. Decreased mating aggregation size is predicted to lead to an increased effect of sperm limitation at constant fishing mortality and effort. Marine protected areas ... [ABSTRACT FROM AUTHOR]