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Alonso-Fernandez A.,CSIC - Institute of Marine Research | Alos J.,University of the Balearic Islands | Grau A.,Laboratori dInvestigacions Marines i Aquicultura | Dominguez-Petit R.,CSIC - Institute of Marine Research | Saborido-Rey F.,CSIC - Institute of Marine Research
Marine and Coastal Fisheries | Year: 2011

The usefulness and importance of histological techniques in reproductive studies have been widely discussed for gonochoristic fish species. In the case of hermaphroditic fishes, histology is a particularly important tool for the proper identification of sexual pattern (i.e., sequential, simultaneous, or nonfunctional hermaphroditism).We used a histological approach to describe hermaphroditism, dynamics of follicle development, and spawning patterns in three species from the northwestern Mediterranean Sea (Balearic Islands, Spain): the Mediterranean rainbow wrasse Coris julis (sequential hermaphrodite), painted comber Serranus scriba (simultaneous hermaphrodite), and annular sea bream Diplodus annularis (nonfunctional hermaphrodite). Development of secondary growth follicles was asynchronous in all three species, and similar peaks in spawning activity occurred between May and July. However, notable differences in sexual cycle and egg production were found. For the painted comber, hydrated follicles were present in ovarian tissue almost every day during the peak of the spawning season, suggesting daily spawning and increasing the chances of autofertilization unless a mechanism to avoid this action is present in this species. Intersexual Mediterranean rainbow wrasses were identified, and the size and age at sex change were estimated to be 132 mm total length and 4 years, respectively. Previous investigators have concluded that the annular sea bream is a protandric hermaphrodite, but our results indicate nonfunctional hermaphroditism. These three species are of little commercial interest and are considered to be bycatch by the artisanal fleet, but they are vulnerable to the impacts of some recreational angling activities. Currently, no specific management plan has been developed for these species. We address the importance of describing sexual pattern and its implications for future conservation efforts. © American Fisheries Society 2011.

Gil M.M.,Laboratori dInvestigacions Marines i Aquicultura | Gil M.M.,CSIC - Mediterranean Institute for Advanced Studies | Palmer M.,CSIC - Mediterranean Institute for Advanced Studies | Grau A.,Laboratori dInvestigacions Marines i Aquicultura | And 3 more authors.
Journal of Fish Biology | Year: 2014

The performance of juvenile Argyrosomus regius released off the coast of Mallorca Island (Balearic Islands, Spain) was assessed by comparing the body condition, stable isotope signature and stomach contents of aquaculture-produced A. regius that had been released, fished and returned by fishermen after spending from a few days to >1 year at liberty with A. regius reared under controlled conditions on two contrasting diets (well-fed and unfed). During the first 40 days of the experiment, the condition index (KR) of the returned A. regius and the unfed A. regius followed the same decreasing trend. Thereafter, the KR values of the returned A. regius were significantly higher than those of the unfed A. regius but never reached the values of well-fed A. regius. The δ13C signal of the returned A. regius clearly increased (in comparison with the well-fed A. regius) after they had spent a few months at liberty. The temporal pattern depicted by the stable isotopes and the most likely prey composition inferred from this pattern strongly suggest a shift in diet. The stomach contents of the returned A. regius that had spent <100 days at liberty consisted almost exclusively of decapods. The diet of the few returned A. regius that had spent >100 days at liberty consisted entirely of fishes. Wild A. regius from the remaining fishery on the Spanish coast exhibited the same ontogenetic diet shift from invertebrates to fishes, but at a smaller size threshold. Overall, the results demonstrated that culture-reared A. regius experience adverse conditions during the first days after release into the wild but that at least some A. regius are able to adapt to the natural environment after a few months at liberty. © 2013 The Fisheries Society of the British Isles.

Gil M.M.,Laboratori dInvestigacions Marines i Aquicultura | Gil M.M.,CSIC - Mediterranean Institute for Advanced Studies | Palmer M.,CSIC - Mediterranean Institute for Advanced Studies | Hernandez M.D.,IMIDA Acuicultura. Consejeria de Agricultura y Agua de la Region de Murcia | And 5 more authors.
Scientia Marina | Year: 2015

The resilience of released hatchery-reared specimens increases with age and size, but production costs are also greater for these individuals. Therefore, for a given budget, the consequences of increasing age and size impose a trade-off between producing a large number of vulnerable (small) fish or a small number of resilient (large) fish. Once the optimal size for releasing fish has been defined, the choice of rearing protocol will determine the number and quality of the fish that can be released. In this study, different rearing protocols were compared using meagre juveniles (Argyrosomus regius), which are presently the target of a restocking programme conducted in the Balearic Islands (western Mediterranean). Seven different diets were compared during the grow-out phase to identify the diets that produced good-quality juveniles of a given size at the lowest cost. Most of the diets produced juveniles of suitable biological quality in terms of growth, fish condition (relationships between length and total weight, liver weight and mesenteric fat weight) and tissue biochemical composition. A semi-moist diet (Diet G) provided the best growth rate, closely followed by commercial meagre pellets (Diet A). In contrast, the cost of growing fish with Diet A was lower for any possible size at release. This study demonstrates the need to consider both growth rate and production cost to select the rearing protocol that maximizes the number of juveniles that can be produced for a given budget and desired release size. These considerations will ultimately increase the chance of success of restocking programmes. © 2015 CSIC.

Duran J.,Laboratori dInvestigacions Marines i Aquicultura | Palmer M.,CSIC - Mediterranean Institute for Advanced Studies | Pastor E.,Laboratori dInvestigacions Marines i Aquicultura
Aquaculture | Year: 2013

In this paper, we report the first successful attempt to grow Maja squinado in captivity from larvae to sexual maturity. Eggs were obtained from wild-caught crabs in the laboratory. The larvae-juveniles were reared together to an age of 150-210days. Subsequently, up to seven consecutive molts were individually monitored to an age of 490days maximum. Based on these individually monitored crabs, a growth model was developed to predict the molting probability and molting increment as a function of sex, temperature, and pre-molt size. The predictions of the model show that the females (25-75% percentiles of the 7th monitored molt: 106 to 139mm and 456 to 654days) appear to have a lower but less variable growth rate than the males (98 to 152mm and 378 to 518days). The size at first maturity for females was estimated to be 103.6mm. Although the model was parameterized using individuals raised in aquaculture, data and models of this type are very scarce for crustaceans and will be useful for managing the ongoing stocking program for M. squinado in the Balearic Islands. In addition, the full life cycle of the Mediterranean spider crab was completed in captivity. The mating of laboratory-reared crabs was repeatedly observed, and viable eggs and larvae were obtained from laboratory-reared adults. © 2013 Elsevier B.V.

Alos J.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Puiggros A.,CSIC - Mediterranean Institute for Advanced Studies | Diaz-Gil C.,CSIC - Mediterranean Institute for Advanced Studies | Diaz-Gil C.,Laboratori dInvestigacions Marines i Aquicultura | And 4 more authors.
PLoS ONE | Year: 2015

No-take marine protected areas (MPAs) are assumed to enhance fisheries catch via the "spillover" effect, where biomass is exported to adjacent exploited areas. Recent studies in spearfishing fisheries suggest that the spillover of gear-naïve individuals from protected to unprotected sites increases catch rates outside the boundaries of MPAs. Whether this is a widespread phenomenon that also holds for other gear types and species is unknown. In this study, we tested if the distance to a Mediterranean MPA predicted the degree of vulnerability to hook and line in four small-bodied coastal fish species.With the assistance of underwater video recording, we investigated the interaction effect of the distance to the boundary of an MPA and species type relative to the latency time to ingest a natural bait, which was considered as a surrogate of fish naïveté or vulnerability to fishing. Vulnerability to angling increased (i.e., latency time decreased) within and near the boundary of an MPA for an intrinsically highly catchable species (Serranus scriba), while it remained constant for an intrinsically uncatchable control species (Chromis chromis). While all of the individuals of S. scriba observed within the MPA and surrounding areas were in essence captured by angling gear, only one fifth of individuals in the far locations were captured. This supports the potential for the spillover of gear-naïve and consequently more vulnerable fish from no-take MPAs. Two other species initially characterized as intermediately catchable (Coris julis and Diplodus annularis) also had a shorter latency time in the vicinity of an MPA, but for these two cases the trend was not statistically significant. Overall, our results suggest that an MPA-induced naïveté effect may not be universal and may be confined to only intrinsically highly catchable fish species. This fact emphasizes the importance of considering the behavioural dimension when predicting the outcomes of MPAs, otherwise the effective contribution may be smaller than predicted for certain highly catchable species such as S. scriba. © 2015 Alós et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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