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Responsible stock enhancement initiatives require baseline data of wild population demographic conditions that can be used in testing management outcomes. This study provides the first fishery-independent assessment of length- and age-based biological characteristics of exploited populations of Platycephalus fuscus in eastern Australia prior to stock enhancement. Sampling was conducted over seven estuaries spanning seven degrees of latitude and the geographical range of proposed stock enhancements. Populations in all estuaries showed evidence of length and age truncation, especially those subject to commercial fisheries where young individuals of both sexes dominated populations. Maximum longevities were 12 and 11 years for females and males respectively, but few females >5 years and males >3 years were generally sampled. Females dominated populations, and on average, the mean lengths and ages of females were greater than males within each estuary and across all age classes. Sexually dimorphic variation in growth was evident across all estuaries, with females attaining greater maximum lengths than males. Estuary-specific differences in individual growth were not identified. On average, over 50% of females sampled in each estuary were > the minimum legal length (MLL), but the opposite was evident for males. In contrast, over 25% of males in each estuary were > the mean length at maturity (L50), whereas in all but one estuary <13% of the females were > the L50. Stocked male and female P. fuscus should recruit to the fishery in 2 and 3 years, and contribute to the spawning stock in 1.5 and 4.5 years, respectively. This study provides important historical baseline data that can contribute to testing stock enhancement outcomes on populations. [ABSTRACT FROM AUTHOR]

Abstract Atlantic sturgeon (Acipenser oxyrinchus), also known as Baltic sturgeon, is considered missing or extinct in German waters. Current conservation efforts focus on re-stocking activities, but classical hatchery rearing may reduce the fitness of the respective juveniles. In this study, we evaluated if foraging efficiency can be improved by short term training. Over a period of 14 d, we kept individuals of the training group in a raceway and fed them chironomids buried in a small sand spot to stimulate benthic feeding behavior while fish of the control group were fed in tanks without substrate. Thereafter, each fish was transferred to a raceway entirely covered with sand. For feeding, chironomids were randomly buried in the sand. During the first 7 days, trained fish recovered the feed significantly faster than untrained fish of the control group. Gene expression revealed an up-regulation in neurod1 in all brain regions after 14 d of training. Thus, this study suggests that foraging efficiency can be improved through short-time training thus improve fitness upon restocking into the wild. Highlights • Conservation focus on re-stocking activities, but classical hatchery rearing may reduce the fitness of juveniles. • Alternative hatchery practices should aim at producing fitter fish for re-stocking. • Short-term foraging training reduces the time to successfully forage and stimulates brain plasticity and cognition in Baltic sturgeon. • Foraging efficiency can be improved through short-time training thus improve fitness upon restocking. [ABSTRACT FROM AUTHOR]

In the last decades many of negative effects, as different hydraulic structure, hydropower plant, and dams and river regulation influenced on the Danube river system. These artificial structures alter the water dynamic of river, the morphology of the bed-load, and the river bank. As a result of the changed hydro -ecology conditions, have been degradated the important spawning sites and habitat of sturgeon. The crucially migration to the the upper-river basin of the sturgeon was restricted, after the construction of the two dams of Iron Gate. Of the five native sturgeon species, only the sterlet (A. ruthenus) has naturally breeding population in the Hungarian region of the Middle-Danube basin. However, the size of their population is extremely decreasing. The HAKI ex situ gene bank reserves nearly 200 sexually matured sterlet specimens however, no further information about the genetic structure of this stock is available. The aim of this study was to gain a preliminary knowledge on the genetic structure of brood stock in relation to the wild population. Four microsatellite loci were used this far to assess the genetic diversity of two sterlet population. 57 specimen originated from HAKI brood stock (25% of the total brood stock), and 37 individual sampled in 2016 from the Hungarian part of the Danube. Allele frequency, number of polymorphic loci, effective alleles as well as, expected and observed heterozygosity were determined by GenAlex statistical software package. Altogether 54 alleles were detected in the two observed populations. Based on four microsatellite loci data, there is no genetic differences (Fst=0,051) between the two populations this far. In the future this genotyping data can be used to improve the genetic management of the ex-situ gene bank, and it will be useful in the restocking program also. Although, for more detailed and reliable genetic results, genotypic data from further microsatellite loci are needed. [ABSTRACT FROM AUTHOR]

Abstract: The effect of three mono‐specific and four combinations of the diatoms Chaetoceros muelleri, Chaetoceros calcitrans, and the chlorophyte Tetraselmis suecica on survival, development, and dry weight of the western school prawn, Metapenaeus dalli, was assessed from protozoea I until mysis I. The development and dry weight of larvae were significantly greater when fed diets comprising C. muelleri and/or T. suecica. A fourth diet, consisting of all three microalgal species also performed just as well. Survival alone was a poor measure of the performance of the various diets. Larvae fed with C. calcitrans, either alone or in a mixed diet with either C. muelleri or T. suecica, had significantly slower development and lower dry weight. Overall performance, assessed using the normalized biomass development index, determined that both mono‐specific and mixed diets containing C. muelleri and T. suecica were among the best for M. dalli larvae. These results for M. dalli are consistent with those found for commercially grown penaeid prawns. This study enhances the limited knowledge on the feeding requirements of metapenaeid prawn larvae. Moreover, the results will help improve hatchery methods for the aquaculture‐based enhancement of M. dalli in the Swan‐Canning Estuary and potentially increase the abundance of this iconic recreational species. [ABSTRACT FROM AUTHOR]

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Young eel, recruiting from the ocean towards Europe, are most abundant along the Atlantic coast of France. Since 1840, attempts have been made to redistribute them from the areas of highest abundance to other countries and farther inland. This 'restocking' has been troubled by technical constraints (e.g. mode of transport and maximum distance eel can be shipped alive), wars (e.g. the Franco-Prussian War and World Wars One and Two) and, in recent decades, by shortage of supply due to the general decline of the eel stock all across Europe. Though objectives and procedures have changed considerably over the years, the recurring aim has been to increase production and, in that way, to 'faire mieux que la nature'. We document the historical development of these efforts from their inception, and contrast the achievements to the objectives. Except for the 1952-1990 period in Eastern Europe, restocking has probably added only slightly to the natural production. As successful as restocking might have been locally, it has not markedly changed the overall trends and distribution patterns or halted the general decline of the stock and fishery. Poor post-evaluation, frequent technical innovation and a constant renewal of the countries and people involved have kept the promise of a better future alive for 175 years. [ABSTRACT FROM AUTHOR]

Introduction of non-indigenous taxa by anthropogenic activities may lead to the generation of hybrid forms and cause genetic pollution of native species. Populations of different Salmo species are threatened in Italy by hybridization and introgression caused by allochthonous lineages introduced since historical times. In particular, Salmo marmoratus is currently sympatric with domestic lineages of Salmo trutta in most of its native geographical range and reproductive interfecundity between the two taxa is seriously threatening the genetic purity of the endemic species. To fulfill conservation purposes and fisheries management, an investigation based on single and multilocus DNA fingerprinting was carried out both to assess marble trout genetic diversity and the method’s amenability to restocking practices. RFLPs (Restriction Fragments Length Polymorphisms) and SNPs (Single Nucleotide Polymorphisms) in mitochondrial 16 S rDNA, D-loop , and nuclear LDH-C1* sequences were genotyped in more than 350 samples collected from different hatcheries in Northern Italy. The combination of the three markers allowed the selection of putative pure individuals of S. marmoratus to be submitted to additional highly polymorphic AFLPs (Amplified Fragment Length Polymorphisms) analyses. Additional benefits of AFLPs over other techniques emerged in connection with their potential power for fish stock identification. In fact, 52% of all analyzed samples were potentially pure marble trout, 4% were pure Atlantic trout and 44% were hybrids showing different combinations of haplotypes/genotypes. The combined approach demonstrated improved resolution to reveal hybridization not detected by classical diagnostic markers, and to select breeders for reintroduction programs. [ABSTRACT FROM AUTHOR]

Marking of fish otoliths with oxytetracycline and tetracycline is a widely used method to evaluate the effectiveness of stocking operations. Available protocols for the labeling of fish specify a number of factors influencing mark quality and potential risk for fish during marking. This study investigates the influence of water hardness on mortality of freshwater fish during marking with OTC. In order to pursue this question complexation of OTC with Mg and Ca cations was measured spectrophotometrically. Furthermore, zebrafish ( Danio rerio) were immersed in OTC solutions (1200 mg/L; 48 h immersion) combined with varying levels of water hardness (5.5, 15.5, 25.5, 32.5°dH). The amount of OTC-Mg-Ca-complexes was positively correlated to water hardness. Moreover, it could be demonstrated that mortality of zebrafish during marking varied as a factor of water hardness. Highest mortalities occurred at the lowest (5.5°dH) and the highest (32.5°dH) tested levels during marking with OTC. [ABSTRACT FROM AUTHOR]

This study has explored whether the restocked fish of a species, which is confined to an estuary, perform as well as its wild stock, and has estimated their contribution to the commercial fishery and egg production. The biological characteristics of the 2001 and 2002 year classes of Acanthopagrus butcheri , which had been cultured and introduced into the Blackwood River in south-western Australia at seven and four months old, respectively, were thus determined from samples collected regularly between 2002 and 2014. The restocked fish could always be distinguished from the wild stock because their otoliths retained the pink colouration of the alizarin complexone with which they had been stained prior to release. Detailed analyses demonstrated the growth and maturity schedules of restocked fish were only slightly inferior to those of the wild stock and the mean gonad weights of the females of these two groups did not differ significantly in any month. As increasing numbers of restocked A. butcheri attained the MLL of 250 mm for retention, their contribution to the commercial fishery increased from 6% in 2005 to 74% in 2010. That contribution subsequently declined to 39% in 2012 and 10% in 2014, due predominantly to the introduction of the very strong 2008 year class in the commercial catches, the first substantial recruitment into the population since 1999. Restocked fish were estimated as contributing ∼55% to the eggs produced in 2008, suggesting that substantial numbers of the 2008 year class were derived from spawning by restocked fish. The results of this and a previous genetic study imply that restocking is an effective and appropriate way for replenishing stocks of an estuarine species such as A. butcheri , especially as its recruitment is highly episodic. [ABSTRACT FROM AUTHOR]

The use of restocking of animals is common practice in the management of populations subject to hunting or recreational fishing. This practice encompasses the release of large numbers of individuals in an area where the species already exists, and thus it can have detrimental genetic impacts on the target populations, especially when captive-reared animals are involved. To better understand this practice and its conservation implications, we chose as a model the wild rabbit ( Oryctolagus cuniculus), a species of high economic and ecological importance, and often under intense management for hunting or conservation purposes, particularly after the large decline caused by rabbit hemorrhagic disease in the 90′s. We studied the genetics of rabbit populations in an area where restocking with captive, wild-domestic hybrids was common. We collected a total of 503 samples from 15 hunting estates that had experienced differing restocking levels, as well as from five locations with no historical restocking and five game farms. All samples were analyzed to determine the mitochondrial DNA (mtDNA) lineage typical of the two European wild rabbit subspecies and domestic rabbit. Game farms and never restocked populations were very different in their haplotypic composition. In restocked areas, the proportion of the domestic lineage was higher when releases were recent and repeated, but this declined rapidly over time, in part due to selective removal by hunting. The extended use of this practice, considering the pronounced genetic and genotypic differences between domestic and wild rabbits, represents a potential danger to natural populations, especially given the marked decrease in wild rabbit numbers experienced in recent years in its original distribution range. [ABSTRACT FROM AUTHOR]

Currently, the distribution of the European native white-clawed crayfish ( Austropotamobius pallipes ) is restricted and fragmented over its range. Many European countries have active programmes for conservation of the species, including reintroduction programmes. Here, we have studied four brooks that were restocked with crayfish coming from population rescue from the Brissionnières after a drought in summer 2009. The aim was to validate the use of Ephemeropteran communities as potential bioindicators to select brooks for crayfish restocking. Restocked brooks were surveyed in 2010 and 2012. All brooks showed chemical and physical parameters in accordance with A. pallipes requirements. Three brooks which had high Ephemeropteran richness including Leptophlebiidae species ( Habrophlebia lauta and Paraleptophlebia submarginata ) have been restocked successfully. No crayfish were observed during the survey in Le Peu, which had only two Ephemeropteran species tolerant of reduced water quality and had no Leptophlebiidae species. Ecological characteristics of Ephemeropteran species and the limitations of their use as bioindicators to select brook for restocking are discussed. [ABSTRACT FROM AUTHOR]

The success of restocking (releasing hatchery-reared juveniles in the wild) depends on the capacity of phenotypes that are already adapted to captivity to readapt to the natural environment. Changes in growth rate after release can be monitored to determine whether released fish are adapting well to the natural environment or failing to adjust to wild conditions. Nevertheless, it is not known whether released individual fish experience a shift in growth rate. Alternatively, the fish showing long-term survival could be those that were already larger before release. This question is relevant for the maximization of stocking success because certain phenotypes (those with a better probability of readapting) could be selected for release. This study compared the somatic growth of released and recaptured meagre, Argyrosomus regius , with control (captive) meagre belonging to the same cohort. Recaptures that had spent less than 3 months at liberty showed the same length-at-age as the control fish, but the length-at-age of many recaptured fish that had spent more than 3 months at liberty was greater than expected. The otolith radius of the growth mark corresponding to the first year of life (i.e., when all fish were still in captivity) was significantly greater for fish that had spent more than 3 months at liberty, indicating that these meagre were larger and had a higher growth rate when they were released. Moreover, the analysis of daily otolith growth before and after release showed that most of the recaptured meagre that had spent less than 3 months at liberty grew an equal or lesser amount in the wild than before release. In contrast, most of the recaptures that had spent more than 3 months at liberty showed a higher growth rate after release. Therefore, results are discussed in light of the combined effect of differential survival and increased growth, although the low sample size requires interpreting the results carefully. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A genetic analysis was conducted of the critically endangered migratory catfishPseudoplatystoma corruscansfrom the São Francisco River basin, the basin with the second highest hydropower capacity installed in Brazil. The analysis was conducted using five microsatellite markers previously described in the literature. Genetic diversity was analyzed and compared in three wild populations and a captive broodstock for a restocking program. Catfish populations of this river showed high genetic diversity in terms of heterozygosities; however, only half of the total number of alleles found in other basins were detected. Seven private alleles occurred in this basin and most of them at low frequencies, indicating they are under threat of extinction. OverallFSTand assignment test suggested low differentiation among the three wild populations; however, a marked distinction between these populations and the captive broodstock was observed. The number of alleles and low average relatedness estimates found for the captive population suggest that it could be used for restocking in areas where the wild population has collapsed, but should not be used for stock enhancement in areas where the wild population is extant. These results are important as a reference for genetic aspects that should be considered in fish management activities. [ABSTRACT FROM PUBLISHER]

In the South American Neotropics, several fish taxa with distributions ranging over multiple river basins might actually represent cryptic species or distinct evolutionarily significant units (ESUs). Defining hidden genetic diversity within species is of great significance to inform on programs aimed at maintaining the evolutionary potential of natural populations and to conduct appropriate fisheries management. This is particularly important in commercially exploited species, such as the 'surubim' catfishes (genus Pseudoplatystoma). Here, based on evidence of reciprocal mtDNA monophyly and significant nuclear divergence in eight microsatellite markers we report on two ESUs in the widely distributed Pseudoplatystoma corruscans. The implications of these results for the conservation management, traceability of fish products and for identifying breeders for restocking programs in this important apex predator are discussed. [ABSTRACT FROM AUTHOR]

An enhancement programme based on stocking 0+ year age-class Atlantic salmon Salmo salar, conducted in the River Bush, Northern Ireland, U.K. over the period 1996-2005, was reviewed with reference to the performance and biological characteristics of wild fish. Wild ova to 0+ year fry (summer) survival was c. 8% with subsequent wild 0+ year fry-to-smolt survival c. 9%. Stocked unfed 0+ year juveniles gave c. 1% survival to smolt whilst fed 0+ year S. salar stocked in late summer exhibited survival at c. 5%. Stocking with unfed and fed fry contributed to increased smolt production and helped attain local management objectives between 2001 and 2005. Significant differences in biological characteristics were observed between wild and stocked-origin fish. Wild-smolt cohorts were dominated by 2+ year age-class fish on the River Bush whilst smolts originating from fed fry mostly comprised younger 1+ year individuals. The mean mass of 1+ year smolts derived from stocked fed fry was significantly lower than that of wild 1+ year smolts, although these differences were not evident between older age classes. Differences in run timing between wild smolts and smolts derived from stocked fry were also apparent with the stocked-origin fish tending to run earlier than wild fish. Although the stocking exercise was useful in terms of maximizing freshwater production, concerns over the quality of stocked-origin recruits and the long term consequences for productivity are highlighted. [ABSTRACT FROM AUTHOR]

Abstract: Behavioural studies comparing hatchery and wild-caught fish are useful to improve selection for aquaculture and restocking programmes. We examined swimming behaviour characteristics in wild captured and domesticated sea bass juveniles before and after eliciting a startle response at 8 different ages and always on naive individuals. We specifically investigated whether domestication impacts juvenile sea bass behaviour and whether the first months of captivity induce behavioural modifications in wild juveniles. An apparatus was designed to mimic a predator attack by presenting a sudden visual and mechanical stimuli simultaneously in 8 arenas where single individuals were placed and video recorded. The reactivity response was evaluated and different swimming variables including angular velocity, total distance travelled, mean velocity, immobility and distance from stimulus point were analysed from videos taken 5min before stimulus actuation, 5 and 15min after. Otolith readings showed that wild and domesticated juveniles were of similar age (∼55 days at the start of the experiment and ∼125 at the end of experiment). There were consistent behavioural differences (e.g. higher angular velocity and distance from stimulus point in wild fish) demonstrating that domestication reduces flight response behaviour. There were also similarities between both fish origins (similar response to stimulus actuation: decrease of total distance travelled and mean velocity, increase of angular velocity and immobility). A decrease over time in reactivity and variability in swimming responses among fish of both origins showed that captivity only does not fully explain wild fish behaviour changes and ontogenic modifications are likely interplaying. [Copyright &y& Elsevier]

Turkey has, with geographic location including Istanbul and Çanakkale straits the system, 178,000 km in length streams, 906,000 ha of natural lakes, and 411,800 ha of dam lakes, and 28,000 ha of ponds due to richness inland waters which include freshwater fish. The fingerling fish (fry) were restocked approximately 250,000,000 in natural lakes, dam lakes and ponds for fisheries between years of 1979 and 2005. Canakkale has rich freshwater potential with 7 major rivers (Büyükdere, Karamenderes stream, Kavak brook, Kocacay stream, Saricay stream, Tuzla brook, Umurbey brook), 7 Dam Lakes (Atikhisar, Zeytinlikoy, Bayramic, Bakacak, Tayfur, Umurbey and Yenice-Gönen Dam lakes). In the studies, it has been determined that 15 fish species belonging to 6 families (Anguillidae, Atherinidae, Salmonidae, Cobitidae, Cyprinidae and Poecilidae) can be found in reservoirs. Fish restocking of the activities of the reservoir until today approximately 1,120,000 (Cyprinus carpio L., 1758) is introduced. In this study, the activity of Canakkale province in the fish restocking and reservoir exploiting possibilities were discussed in view of reservoir fisheries potential which is used insufficiently today. [ABSTRACT FROM AUTHOR]

Marine stock enhancement is a set of management approaches involving the release of cultured organisms to enhance or restore fisheries. Such practices, including sea ranching, stock enhancement, and restocking, are widespread, of variable success, and often controversial. A set of principles aimed at promoting responsible development of restocking, stock enhancement, and sea ranching has been proposed by Blankenship and Leber [American Fisheries Society Symposia 15: 167-175 (1995)], and has gained widespread acceptance as the 'Responsible Approach'. Fisheries science and management, in general, and many aspects of fisheries enhancement have developed rapidly since the responsible approach was first formulated. Here we provide an update to the Responsible Approach in light of these developments. The updated approach emphasizes the need for taking a broad and integrated view of the role of enhancements within fisheries management systems; using a stakeholder participatory and scientifically informed, accountable planning process; and assessing the potential contribution of enhancement and alternative or additional measures to fisheries management goals early on in the development or reform process. Progress in fisheries assessment methods applicable to enhancements and in fisheries governance provides the means for practical implementation of the updated approach. [ABSTRACT FROM AUTHOR]

The swimming performance of wild and hatchery-reared smolts of two salmonid species was investigated. Wild Atlantic salmon smolts (WS) and brown trout smolts (WT) of equal size were caught in fish traps during migration. Hatchery-reared smolts of both species (HS and HT for salmon and trout respectively) were first generation offspring from wild broodstock. The swimming performance of individual smolts from the four groups (WS, HS, WT, HT) was tested three consecutive times using a swimming flume with water flowing at a start rate of 0.16 m·s−1 and a constant acceleration rate of 0.167 cm·s−2 (10 cm·s−1·min−1). Wild caught smolts of both species performed significantly better than those reared in hatchery conditions. The WS group were observed to maintain an average swimming speed ( Uburst) that was 30% faster than the HS group, whereas the wild trout smolts were superior to HT by approximately 25%. Repeated measures revealed species-specific exhaustion patterns. Brown trout smolts maintained consecutive Uburst indicating significant stamina compared with Atlantic salmon smolts that were found to be exhausted by the initial trial. [ABSTRACT FROM AUTHOR]

The dusky grouper (Epinephelus marginatus) is an endangered marine fish for which a restocking program has been undertaken in the Mediterranean Sea. Genetic variation at six microsatellite loci was assayed to help plan preservation of genetic diversity after release of hatchery-reared juveniles. We estimated relatedness and effective population size within two groups of captive broodstock, assessed genetic variability of these broodstock and F1 juveniles compared to natural populations, and investigated genetic relationships between hatchery-reared and wild specimens inhabiting the release site. On average, no relatedness was found within captive broodstock and a potentially high number of effective breeders was assessed (Nb = 86.9; CI 95% = 46.0-451.2). However, very few breeders (N = 7) spawned successfully, and a positive degree of relatedness (rW = 0.0297) was found among this particular subset of individuals. Genetic variability parameters were reduced for the broodstock and F1 juveniles, although not significantly. Genetic differentiation was detected among released juveniles and wild conspecifics collected 75 km away from the target area. However, the pattern of genetic distances from other wild populations justifies the choice of the broodstock as the best alternative donor stock. [ABSTRACT FROM AUTHOR]

Natural populations of global inshore fisheries are coming under heavy pressure, primarily due to overexploitation and habitat degradation. Stock enhancement of hatchery-reared seeds is perceived as an alternative strategy to enhance the regeneration process. The Aquaculture Department of the Southeast Asian Fisheries Development Center in the Philippines has been implementing activities related to stock enhancement of donkey's ear abalone (Haliotis asinina), mud crabs (Scylla spp.), giant clam (Tridacna gigas), and seahorses (Hippocampus spp.). Seed production techniques for abalone including a diet tagging method were established, and juvenile abalone were released and monitored in a marine protected area. Mud crabs conditioned before release had higher recapture rates compared to the non-conditioned crabs, which can be translated to higher survivorship. Giant clams stocked at 8-10 cm shell length have high survival 4 mo after stocking (90%), with initial mortalities occurring within the first few days due to transportation stress. Seed production trials for seahorse have begun. [ABSTRACT FROM AUTHOR]

Abstract: For almost 20 years, the Marine Science Institute (MSI), University of the Philippines, has been culturing giant clams to restore depleted populations of these large bivalves in the Philippines, and to promote giant clam farming as a sustainable livelihood. Restocking activities were done in collaboration with local groups by providing training in the culture and ocean rearing of giant clams, and by implementing a “users pay” approach. Initially, a variety of giant clam species was used but once F1 broodstock of Tridacna gigas were reared, restocking focused on this species due to its scarcity and fast rate of growth. About 20000 T. gigas were placed on coral reefs. In addition, >50000 clams (T. gigas, T. squamosa, T. derasa, T. crocea, T. maxima and Hippopus hippopus) were distributed through other means. Altogether, >40 sites throughout the Philippines received cultured giant clams. Grow-out trials to test the viability of supplying giant clams for the aquarium trade to create new sources of income were conducted successfully with a group of fishers in Bolinao, Pangasinan. However, this initiative encountered legal obstacles when the government regulatory agency prohibited the export of cultured clams, regarding this as a threat to the conservation of wild individuals. The long experience in culturing and restocking giant clams in the Philippines provides many lessons for other countries wishing to restore stocks of these large bivalves. Particular care needs to be given to selection of release sites, negotiations with participating groups to safeguard the released clams, adequate transfer of technology to collaborators, and transport of large clams from nursery areas to release sites. [Copyright &y& Elsevier]

Abstract: The demand for fish is expected to rise substantially by 2020. Although aquaculture must provide much of the additional fish, it remains to be seen whether restored or enhanced capture fisheries can also help fill the projected gap in supply. The key challenges for capture fisheries involve reducing fishing effort, removing excess fishing capacity and building the institutional arrangements needed to restore spawning biomass to more productive levels, and to reverse degradation of the supporting habitats. Two interventions, based largely on hatchery technology, have the potential to reduce the time needed to rebuild some severely over-exploited fisheries, or improve the productivity of other ‘healthy’ fisheries. These interventions are ‘restocking’, which involves releasing cultured juveniles to restore spawning biomass to levels where the fishery can once again support regular harvests, and ‘stock enhancement’, which involves release of cultured juveniles to overcome recruitment limitation. However, despite the potential of these interventions, few restocking and stock enhancement programmes have met expectations. The main problems have been a pre-occupation with bio-technical research at the expense of objective analysis of the need for the intervention, and failure to integrate the technology within an appropriate management scheme that has the participation and understanding of the users. The papers presented at the Special Symposium on this subject at the Seventh Asian Fisheries Forum provide a series of valuable lessons to guide objective assessment of the potential for restocking and stock enhancement. They also show how to implement these interventions responsibly and effectively where they are deemed to add value to other forms of management. Above all, these studies demonstrate that restocking and stock enhancement programmes are applied in complex human–environment systems, involving dynamic interactions between the resource, the technical intervention and the people who use it. [Copyright &y& Elsevier]

The genetic variability of 11 French pike Esox lucius populations from rivers or extensive aquaculture ponds was analysed using seven microsatellite markers. The fish stocking of eastern European pike in French rivers is widespread, so five supplementary populations from this region were also analysed. Genetic variability within the French population was small, and similar to that previously found in Europe for this species. French populations from stocked rivers and extensive farms formed a genetically homogeneous group, and did not diverge from most eastern European samples, which may reflect either ancestral polymorphism or a complete introgression of French populations by introduced stocks. Bayesian analysis of the admixture between populations enabled identification of the French populations that were likely to be affected by introduced stocks (of local or foreign origin). Three genetically distinct evolutionary branches were identified: continental Europe, Danube basin, and south-western France. The last is a new finding in the species which needs to be further explored by comparisons with wild populations at other sites. [ABSTRACT FROM AUTHOR]