The ovaries of 31 franciscana dolphins (19 immature and 12 mature) by-caught in coastal waters of Argentina were examined to describe the reproductive biology. No ovarian polarity was found, both ovaries were functional and showed similar amounts of corpora. A positive trend was observed between the number of corpora and age (3–8 years old), indicating that ovulation scars are detectable for at least 4 years, and a ovulation rate of 0.39 was found for the sampled population. Age, length and weight at sexual maturity were estimated at 3.92 ± 0.09 years, 133.47 ± 11.11 cm and 32.68 ± 2.72 kg, respectively. The annual pregnancy rate was 0.36 ± 0.02 (95% CI = 0.10–0.65). The proportion of lactating and resting females found were 0.25 and 0.33 respectively. These outcomes constitute the first reproductive and life history information on franciscana dolphins from the southernmost population and are important in relation with adequate conservation management plans for this small cetacean.

Societal pressure to ban surgical castration of male piglets is rising due to animal welfare concerns, thus other methods to prevent boar taint need to be explored. Genetic selection against boar taint appears to be a long-term sustainable alternative. However, as boar taint is linked to reproductive hormones, it is important to consider possible negative side effects such as delayed sexual maturity or changes in behaviour. We reported earlier that the melanocortin-4 receptor (MC4R) marker can be used to reduce boar taint levels in fat of boars. The objective of this study was to evaluate whether MC4R marker-assisted selection for lower boar taint prevalence affects plasma levels of boar taint compounds and testosterone; sexual maturity; behaviour; skin lesions; and lameness in boars and gilts. Using an intervention study with a 2×2 design, 264 boars and gilts differing on position 893 of the MC4R gene (AA v. GG) were compared. The MC4R polymorphism did not affect the plasma concentration of either androstenone or testosterone at different time points, whereas the concentration of skatole was significantly lower (P=0.003) and the concentration of indole tended to be lower (P=0.074) in GG compared with AA boars. A higher percentage of gilts of the GG genotype were in puberty at slaughter age compared with AA gilts (P<0.001). The age of the boars at sexual maturity (as indicated by the first positive preputial smear test) did not differ between AA and GG boars. In contrast, weight of GG boars at sexual maturity tended to be lower (P=0.065). During the period from 6 weeks of age to slaughter, boars and gilts of the GG genotype showed more playing behaviour (P=0.015) and less passive and feeding behaviour (P=0.003). They showed more skin lesions on their back and caudal area (P=0.022), and tended to show more skin lesions on their head and anterior area (P=0.093) compared with AA animals. In conclusion, the polymorphism in the MC4R gene can be used as a marker without negative effects on reproduction characteristics in boars and gilts. Genetic selection towards a lower prevalence of boar taint will lead to more active pigs with more skin lesions. Management strategies may therefore be necessary to reduce skin lesions in the selected animals.

Thunnus alalunga is an important commercial tuna species widely distributed in the three major oceans and the Mediterranean Sea. The Mediterranean population is currently classified as a data-poor stock and little is known about its basic life history parameters. This study provides the first detailed information on some aspects of the reproductive biology of T. alalunga from the western Mediterranean Sea. A total of 16 104 specimens were measured between 2005 and 2012. The overall sex ratio of females to males was 1.1:1, although the ratio was female biased in fish <70 cm fork length (LF) and male biased in those >75 cm LF. Histological analysis of the ovaries (N = 587) and the monthly variation of the gonadosomatic index for both sexes showed that spawning occurred from June to August, which is a much shorter period than the 7 months reported for T. alalunga in tropical oceanic waters. Thunnus alalunga caught during June and July are capable of spawning daily. The gonadosomatic index values for T. alalunga from the western Mediterranean were up to eight times higher than those of T. alalunga from other oceans. Histological examination of the ovaries showed that the minimum length at sexual maturity of females was 56 cm LF, which is considerably smaller than those estimated for other stocks.

A total of 1725 specimens of Dentex maroccanus caught in the eastern coast of Algeria from June 2011 to May 2012 were examined for an age and reproduction study. Total length (TL) ranged from 10.4 cm (16.05 g) to 26.8 cm (300.80 g). The maximum estimated age was 7 years for females and 8 years for males. The growth function of Von Bertalanffy fitted to back-calculated size at age data was: TL = 36.64[1 − e−0.2(t−0.5)] and TL = 37.26[1 − e−0.2(t−0.5)] for females and males respectively. Total length – eviscerated weight (We) relationship was estimated as We = 0.012 TL3.046 for females and We = 0.011 TL3.067 for males, being allometrically positive for both sexes. Sex-ratio was 1:0.9 in favour of females. A five-stage maturity scale based on macroscopic characteristics was identified and used to classify the gonads. The reproductive season, evaluated from a gonadosomatic index, extended from May to September. Fifty per cent maturity of the tested sample was reached at a total length of 14.4 cm TL for females and 15.1 cm TL for males.

The reproductive cycle of the high shore limpet Patella rustica is described based on histological analysis as the primary method of staging gonad development. Sex-ratios, shell length at sexual maturity, gonad developmental stages, mean gonad index and oocyte size were investigated. Males and females were found to differ in size distribution, with females becoming more prevalent from ~28 mm onwards. The estimated shell length at which 50% of males were sexually mature was 13.1 mm. Patella rustica has only one reproductive cycle per year with a spawning peak between November and December for both sexes, and gonad redevelopment from January. First data on the size–frequency analysis of oocytes for this species are also presented, concurring with the qualitative analysis of the gonad developmental stages. This study presents updated information on the reproductive cycle of this keystone species and provides the first account of the reproductive biology of P. rustica in the Adriatic Sea.

The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic Ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin by-caught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex-ratio of the by-caught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution.

Benthosema pterotum is a dominant myctophid in the shelf region of the East China Sea (ECS). They are a key species linking secondary producers and upper trophic levels. We examined the reproductive biology of B. pterotum in the ECS, based on 3065 specimens (10.7–54.8 mm standard length (SL)) sampled during cruises in 1999 and 2004–2009 to enable data over a 12 month cycle to be assessed. Between 14 and 30 mm SL, the ratio of females to males was ~1:1; it increased with SL, and all individuals ≥46 mm SL were females. The gonadosomatic index (GSI) at 50% sexual maturity of females and males was 3.91 and 0.24, respectively. Based on this criterion, females and males can mature at sizes larger than 28 mm and 24 mm SL, respectively. Although mature females having GSI ≥3.91 occurred over nine months (May–January), mean GSI of females peaked sharply during August–September, i.e. the primary spawning period. The hepatosomatic index peaked during April–July, and declined during August–September, indicating storage of materials and energy for reproduction. Based on data from seasonal bottom trawl surveys, small individuals of B. pterotum began to occur abundantly in autumn, and modal body lengths increased progressively during spring–summer, corresponding to the above reproductive seasonality. Oocytes at various sizes were found in mature ovaries, indicating that they are multiple spawners. Egg size at hydration ranged from 0.5 to 0.85 mm. Batch fecundity was positively correlated with SL, and ranged from 253 to 1942 eggs in fish from 30.1–54.8 mm SL.

The relative growths of Persephona lichtensteinii, P. mediterranea, and P. punctata were investigated on the south-eastern Brazilian coast, focusing on differences in the growth rates between immature and mature phases, the onset of morphological sexual maturity, and the breeding seasons of these species. Crabs were collected every two months from January 1991 through to November 1992, from a shrimp fishing boat equipped with two otter-trawl nets. Significant differences in the patterns of body growth were observed between immature and mature phases of all three species. Changes in the growth rates of the chelipeds (males) and abdomen (females) observed for P. lichtensteinii, P. mediterranea, and P. punctata, seem to be related to the puberty moult for both sexes. Males of P. mediterranea and P. punctata reached larger mean sizes of carapace width than females, whereas no difference was recorded for P. lichtensteinii. The body size at which 50% of males attained sexual maturity was also larger in P. mediterranea and P. punctata, and smaller in P. lichtensteinii. The absence of a pronounced sexual dimorphism and the size at the onset of sexual maturity observed only for P. lichtensteinii might be explained by distinct reproductive strategies of males. The presence of ovigerous females during the entire sampling period suggests that all three species have a continuous reproduction pattern at the Ubatuba region. Future studies on the population structure, functional maturity, and mating system should improve the understanding of factors driving the biology and ecology of these species at a subtropical region.

Using soles (Solea solea) infected experimentally with oncomiracidia of the monogenean skin parasite Entobdella soleae, it was found that the parasite begins to assemble eggs at about 85 days post infection and may survive for as long as 6½12 months at 12± 1°C. Growth of the anterior hamuli continues throughout life but the growth rate decreases with time. The oldest (largest) parasites recovered from laboratory soles were similar in size to the largest parasites collected in the wild.

A total of 870 blue sharks ranging from 70 to 349 cm in total length (LT) were sampled from the swordfish longline fishery in the Mediterranean Sea during the period 1998–2003. Males predominated and the sex-ratio (1:1.8) showed an increase in the proportion of males as size of fish increased. Gonad observation revealed that females smaller than 120 cm LT had immature ovaries with no mature oocytes, while mature ovaries with visible yolky oocytes were present in specimens larger than 203 cm LT. Ovary weight varied from 4–137 g and maximum oocyte diameter was 21.1 mm in mature females. All males smaller than 125 cm LT were immature while males larger than 187 cm LT were mature, as indicated by the presence of heavily calcified claspers, which extended beyond the posterior end of the pelvic fins. Length at 50% maturity (L50) was estimated to be 202.9 cm LT for males and 214.7 cm LT for females. Age estimates using caudal vertebrae ranged from 1 to 12 years, while age at 50% maturity was estimated at 4.9 years for males and 5.5 year for females.

The reproductive biology of Scyllarides deceptor was studied along the southern Brazilian coast (27°S 48°W) from December 2002 to December 2003. Samples were collected monthly at Xavier Island, where animals were caught and marked. Fecundity and egg size were estimated from ovigerous females caught also in two adjacent islands, Arvoredo and Aranhas. A total of 98 females was recorded at Xavier Island during the sampling period, 24 of these were recaptured and presented time-at-liberty ranging from 14 to 297 days. Ovigerous females were observed during spring and summer, with the moulting period lasting from late winter to spring. Size at sexual maturity was assessed from 66 females caught during the breeding season and estimated in 85.33 mm of carapace length (CL). Mean fecundity of S. deceptor was estimated in 191,262 eggs (±17,811, SE) for females, on average, 94.74 mm long (±1.86 mm SE) (CL). Fecundity was significantly related to CL (R2 = 0.90) Mean egg size was 0.67 mm (±0.005 mm SE) and did not correlate significantly to CL (P = 0.78). The rocky bottom of Xavier Island was favourable for reproduction, presenting shelter and foraging grounds for the ovigerous females. For management purposes, our results suggest the closure of the S. deceptor fishery from November to January and the capture-size of females to be restricted to animals larger than 90 mm (CL).

Trematomus eulepidotus and T. loennbergii are two of the most common epibenthic fish in the waters of the High Antarctic continental shelf. Since the reproductive biology of these species has not been studied in the Ross Sea, we provide a macroscopic and histological analysis of the reproductive effort and gonadal development in both sexes. Most samples were collected during benthic trawl surveys in the south-western Ross Sea in the 1996 and 1997 summer seasons. The aim of the study was to define the reproductive characteristics of these two sympatric species and to examine the hypothesis that different reproductive strategies mitigate interspecific competition. We found that, in common with most Antarctic notothenioids, both species possess a suite of similar reproductive strategies including delayed sexual maturity, prolonged gametogenesis, group-synchronous oocyte maturation, a single spawning event per year and iteroparity. Both species show a comparable reproductive effort in terms of potential fecundity with between 2000 and 20 000 eggs per female per season. Nevertheless, the two species exhibited a considerable difference in the timing of the breeding season, spawning in summer (T. eulepidotus) and in autumn (T. loennbergii). This gives rise to a mismatch in the time of appearance of larvae in the environment and probably leads to reduced competition.

Germinal-vesicle-stage oocytes enclosed with compact cumulus cell layers (COCs) were recovered from adult or prepubertal minke whale ovaries, and were vitrified in a solution containing 15% ethylene glycol, 15% DMSO and 0.5 M sucrose using either a Cryotop or an open-pulled straw (OPS) as the cryodevice. The post-warm COCs with normal morphology were cultured for 40 h in a 390 mosmol in vitro maturation medium, and oocytes extruding the first polar body were considered to be matured. The proportion of morphologically normal COCs after vitrification and warming was higher when the COCs were cryopreserved by Cryotop (adult origin, 88.4%; prepubertal origin, 80.8%) compared with the OPS (adult origin, 67.7%; prepubertal origin, 64.2%). The oocyte maturation rate was higher in the adult/Cryotop group (29.1%) compared with those of the prepubertal/Cryotop group (14.4%), the adult/OPS group (14.3%) and the prepubertal/OPS group (10.6%). These results indicate that the Cryotop is a better device than the OPS for vitrification of immature oocytes from adult minke whales.

Samples of Chaenocephalus aceratus (Lönnberg) were collected during a trawl survey carried out around the South Shetland Islands in January–February 2002. Fish were caught by commercial bottom trawl fishing down to 500 m depth, using a stratified randomized sampling design. As observed in other recent surveys within the same area, C. aceratus represented one of the predominant species. Overall, 357 specimens ranging from 13 and 67 cm (TL) were selected for the present study. Ages were estimated by counting annuli present in the sagittal otoliths, exposed by grinding and polishing along their sagittal plane. To estimate the precision of age data, we compared blind readings by readers from different institutions. The age range was 1–17 years for females and 1–15 years for males. Von Bertalanffy growth curves were fitted to the estimated age-length data for each sex. The estimated values of asymptotic length L∞ (cm) and K (year−1) were respectively 79.8 and 0.07 for females and 60.0 and 0.09 for males. The growth performance index ranged between 2 and 2.5, similar to that reported in other icefish. Sexual maturity was attained by females and males at about 10 and 9 years old respectively, at about 60% of their maximum estimated age. These results are compared with age and growth data available in the literature for C. aceratus, and discussed in the light of recent commercial exploitation.

An analysis of data for domestic pullets, turkeys, partridges and quail (Coturnix) indicates that, once all birds within a flock have become sexually photoresponsive but before spontaneous sexual development commences, mean age at first egg, egg production in a given period, mean body weight at first egg and mean egg weight increase linearly with age at photostimulation. These relationships are steeper for age at first egg in turkeys, partridges and quail, for egg production in turkeys and partridges and for egg weight and body weight in turkeys than those seen in domestic pullets. This may indicate differential responses by seasonal and non-seasonal breeding birds, species-specific factors such as geographical origins, or may reflect differing periods of artificial selection in the four species. Egg weight in domestic pullets and turkeys is significantly correlated with body weight at first egg.

Nicotine injected intravenously or on pituitary in vivo stimulated maturational gonadotropin (GtH2) secretion in domperidone (D-2 receptor antagonist) pretreated carps. The effective dose was 1 mg·kg−1 and 100 μg·kg−1, respectively. No stimulatory effects of nicotine were observed in normal (non-treated) carps. When nicotine was injected together with gonadotropin releasing hormone (GnRH) analogs (D-Arg6 sGnRH or D-Ala6 LHRH) a clear potentiation effect of nicotine on GnRH analogs' action was observed. This potentiation was seen even in normal fish where nicotine itself had no effect on GtH2 release. A synergism between nicotine and GnRH analogs appeared when low doses of GnRH analogs were used. In domperidone pretreated fish, this synergism occurred after injection of 1 μg·kg−1 of sGnRHa. In normal fish, the same phenomenon was observed after injection of 5 μg·kg−1 of sGnRHa or 20 μg·kg−1 of LHRHa. Higher doses of GnRH analogs mask this effect. Results confirm previous in vitro findings on the stimulatory action of nicotine on GtH2 secretion. They also indicate a possible synergy between nicotine and GnRH as well as an inhibitory influence of dopamine on nicotine's action.

Quelques aspects de la reproduction du listao (Katsuwonus pelamis) dans deux zones distinctes de l'ouest de l'océan Indien ont été étudiés de février 1989 à février 1994. A partir d'échantillonnages faits, soit à bord des thoniers senneurs sur du poisson frais (1 656 individus), soit à la conserverie de Maurice sur des thons décongelés (4 152 individus), les différents stades du cycle sexuel ont pu être précisés. La taille de première maturité sexuelle est atteinte à 41–42 cm (longueur à la fourche) chez les femelles et à 42-43 cm chez les mâles, correspondant à des individus âgés d'environ 1,5 an. L'évolution mensuelle de la proportion des différents stades macroscopiques de maturation des gonades montre que, quel que soit le mois considéré, il y a toujours plus de 70 % des femelles échantillonnées qui présentent des ovaires en fin de maturation (stade IV). Les variations du rapport gonado-somatique (RGS) montrent que la reproduction du listao a lieu toute l'année mais qu'il existe cependant plusieurs périodes d'activité sexuelle plus intense. L'observation histologique de 737 ovaires indique la présence de follicules post-ovulatoires (indicateur de ponte récente) pendant les 2 périodes de mousson, mousson de nord-ouest (novembre à mars) et mousson de sud-est (juin à août) tandis que la proportion d'ovaires présentant des follicules atrétiques est maximale aux 2 périodes d'inter-mousson (avril-mai et septembre-octobre). L'étude du sex-ratio montre que. pour l'ensemble de la période d'étude et pour les deux zones considérées, la proportion de mâles est significativement supérieure à celle des femelles. Ses variations mensuelles semblent indiquer une accentuation de la prédominance des mâles à chaque période de ponte plus intense.