Does trade openness reduce a domestic fisheries catch?

Although trade liberalization may increase a country’s welfare, its specific effect on a country’s fishing industry has not been well studied. By decomposing the effect of international trade into four parts, i.e., scale-technique effects (ST), the indirect trade-induced composition effect (IC), the indirect effect of trade intensity through income (ITC), and the direct effect of trade intensity (DTC), this study empirically investigates the effect of trade openness on country-level fisheries production. To take into account the endogeneity of trade openness and income, we adopt the instrumental variable approach. We find that a rise in trade openness reduces fisheries catch on average. In particular, the long-run effect is large. This result implies that future production is affected by current overfishing through stock dynamics. Our decomposed elasticities indicate that the ST and ITC dominate in the trade elasticity of fisheries catch. While ST implies that overfishing would be affected by trade, ITC may either establish an “overfishing haven”, similar to a “pollution haven” in the environmental literature, or production shift of fisheries to countries with lax regulation to pass stringent regulation, which is more likely to occur in high-income countries.     

Does acidification lead to impairments on oxidative status and survival of orange clownfish Amphiprion percula juveniles?

Fish Physiology and Biochemistry - The nitrification process in recirculating aquaculture systems can reduce water pH. Fish can also be exposed to water acidification during transport, an important...     

Can catch share fisheries better track management targets?

Fisheries management based on catch shares – divisions of annual fleet‐wide quotas among individuals or groups – has been strongly supported for their economic benefits, but biological consequences have not been rigorously quantified. We used a global meta‐analysis of 345 stocks to assess whether fisheries under catch shares were more likely to track management targets set for sustainable harvest than fisheries managed only by fleet‐wide quota caps or effort controls. We examined three ratios: catch‐to‐quota, current exploitation rate to target exploitation rate and current biomass to target biomass. For each, we calculated the mean response, variation around the target and the frequency of undesirable outcomes with respect to these targets. Regional effects were stronger than any other explanatory variable we examined. After accounting for region, we found the effects of catch shares primarily on catch‐to‐quota ratios: these ratios were less variable over time than in other fisheries. Over‐exploitation occurred in only 9% of stocks under catch shares compared to 13% of stocks under fleet‐wide quota caps. Additionally, over‐exploitation occurred in 41% of stocks under effort controls, suggesting a substantial benefit of quota caps alone. In contrast, there was no evidence for a response in the biomass of exploited populations because of either fleet‐wide quota caps or individual catch shares. Thus, for many fisheries, management controls improve under catch shares in terms of reduced variation in catch around quota targets, but ecological benefits in terms of increased biomass may not be realized by catch shares alone.     

Does ‘race to fish’ behaviour emerge in an individual transferable quota fishery when the total allowable catch becomes non‐binding?

Successful individual transferable quota (ITQ) management requires a binding (constraining) total allowable catch (TAC). A non‐binding TAC may result in a shift back towards open access conditions, where fishers increasingly compete (‘race’) to catch their share of the total harvest. This process was examined by comparing fishing fleet behaviour and profitability in the Tasmanian southern rock lobster (Jasus edwardsii) fishery (TSRLF), Australia. Between 2008 and 2010, the TSRLF had a non‐binding TAC and effectively reverted to a regulated, limited‐entry fishery. Fishers' uncertainty about future profitability and their ability to take their allocated catch weakened the security characteristic of the ITQ allocation. The low quota lease price contributed to an increase in fleet capacity, while the more limited reduction in quota asset value proved an investment barrier, hindering the autonomous adjustment of quota towards the most efficient fishers. In the TSRLF, catch rates vary more than beach price and are therefore more important for determining daily revenue (i.e., price x catch rate) than market price. Consequently, fishers concentrated effort during times of higher catch rates rather than high market demand. This increased rent dissipation as fishers engaged in competitive race to fish to be the first to exploit the stock and obtain higher catch rates. The history of this fishery emphasizes the need for a constraining TAC in all ITQ fisheries, not only for stock management, but also to manage the security of the ITQ allocation and prevent unanticipated and undesirable changes in fisher behaviour and fishery profitability.     

Why have global shark and ray landings declined: improved management or overfishing?

Global chondrichthyan (shark, ray, skate and chimaera) landings, reported to the United Nations Food and Agriculture Organization (FAO), peaked in 2003 and in the decade since have declined by almost 20%. In the FAO's 2012 ‘State of the World's Fisheries and Aquaculture’ report, the authors ‘hoped’ the reductions in landings were partially due to management implementation rather than population decline. Here, we tested their hypothesis. Post‐peak chondrichthyan landings trajectories from 126 countries were modelled against seven indirect and direct fishing pressure measures and eleven measures of fisheries management performance, while accounting for ecosystem attributes. We found the recent improvement in international or national fisheries management was not yet strong enough to account for the recent decline in chondrichthyan landings. Instead, the landings declines were more closely related to fishing pressure and ecosystem attribute measures. Countries with the greatest declines had high human coastal population sizes or high shark and ray meat exports such as Pakistan, Sri Lanka and Thailand. While important progress had been made, country‐level fisheries management measures did not yet have the strength or coverage to halt overfishing and avert population declines of chondrichthyans. Increased implementation of legally binding operational fisheries management and species‐specific reporting is urgently required to avoid declines and ensure fisheries sustainability and food security.     

Does feeding time affect fish welfare?

Increased aquaculture production has raised concerns about managing protocols to safeguard the welfare of farmed fish, as consumers demand responsible aquaculture practices to provide ‘welfare friendly’ products. Feeding is one of the largest production cost in a fish farm and can be one of the biggest stressors for fish. Under farming conditions, fish are challenged with artificial diets and feeding regimes, and inadequate feeding conditions cause stress, alteration of normal behavioural patterns, poor performance and eventually diseases and death, which are by no means acceptable neither economically nor ethically. This review aims to highlight the impact of feeding rhythms and feeding time upon physiological and behavioural welfare indicators, which show circadian rhythms as well. Therefore, all these variables should be considered when designing feeding strategies in farming conditions and assessing the welfare state of cultured fish.     

Does propeller turbulence affect the sink rate of baited hooks and their availability to seabirds in pelagic longline fisheries?

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Does waste feed from salmon farming affect the quality of saithe (Pollachius virens L.) attracted to fish farms?

Salmon farms attract large amounts of wild fish, which prey on uneaten feed pellets. The modified diet of the wild fish aggregating at salmon farms may reduce the flesh quality of the fish, influencing the local fisheries. We compared the quality of saithe (Pollachius virens) captured near (farm associated—FA) or more than 5 km away (un‐associated—UA) from salmon farms in Norway. The fish were captured during summer, autumn and spring using two commercial fishing methods (jigging and bottom nets). Overall, the fillet quality of FA saithe was good, although it was clearly reduced for almost 10% of the catch. Moreover, the quality of the FA saithe was significantly reduced compared with UA saithe, but the differences were small. Our results also showed that fish caught with jigging had better quality than fish caught with nets, and that fish that died in the nets were of lower quality than fish that were alive after hauling. There was no clear variation among seasons in fillet quality. Although no major and overall differences in quality were found between FA and UA saithe, reduced quality for even a modest proportion of the fish may influence the value of the total catch.     

Is model selection using Akaike’s information criterion appropriate for catch per unit effort standardization in large samples?

ABSTRACT:   Akaike's information criterion ( AIC ), which is widely used as a criterion of model selection in fish population dynamics, is known to have a bias in not only small samples but also large samples. Consistency was proposed as a property of the information criteria available in large samples. We carried out model selection in ANOVA-type model corresponding to catch per unit effort (CPUE) standardization using consistent information criteria (Bayesian information criterion, Hannan–Quinn, or consistent AIC ), which satisfy the asymptotic desirable property called consistency. The results of the model selections between these consistent criteria and AIC are different. Computer simulations using a linear regression model show that the selection performances of consistent information criteria in large samples are good compared with that of AIC .     

Does the presence of microalgae influence fish larvae prey capture?

The green water technique has been widely shown to improve fish larvae growth, survival and feed ingestion. Therefore, fish larvae (Sparus aurata L. and Solea senegalensis Kaup) feeding behaviour was studied through gut content analysis, when using different species of microalgae, as the ‘green water’ technique. Six treatments were used: Stain – food green stain; Tetra – microalgae Tetraselmis chuii; Iso – microalgae Isochrysis galbana; Tetra Sup –T. chuii supernatant (obtained from centrifugation); Phyto – a microalgae paste, Nannochloropsis oculata, (Phytobloom^®); and C water – clear water, as control. At 9, 16 and 23 days after hatching (DAH) for S. aurata, and 4, 9 and 14 DAH for S. senegalensis, 40 unfed fish larvae were transferred to 3 L experimental tanks, filled with the different ‘green water’ technique. Fish larvae were sampled 2 h after being fed with live prey, anaesthetized and fixed in buffered formaldehyde for posterior gut content determination. Feeding was evaluated by the feeding rate, percentage of larvae with prey items in the digestive tract and feeding intensity, number of prey in each larva digestive tract. Fish larvae feeding ability was influenced by the interaction between light conditions and substances provided by the presence of microalgae during fish larvae development. Sparus aurata was more dependent on microalgae addition than S. senegalensis larvae, which may be related to the type of prey, larval behaviour, ontogeny and physiology. The presence of microalgae influenced the selection of larger prey (Artemia over rotifers) by S. aurata aged 23 DAH.     

How do commercial fishing licences relate to access?

Commercial fishing licences are central to fisheries management systems. They define and allocate harvest rights, place rules upon authorized harvesters and, in some cases, require holders to pay user fees. In this paper, we ask how licences and licensing relate to access, itself a broader concept defined as the opportunity to derive benefits from resources and that draws attention to how institutions and social structures enable and constrain different individuals and groups. Using published literature, reports and publicly available licence data for fisheries off of British Columbia, Canada, we overview licensing history and examine all major commercial licence types in the jurisdiction. Using a network approach, we also describe the diverse suite of licence portfolios held in 2017. Results show that there were 6,563 commercial fishing licences registered by 2,377 unique holders, including a handful that hold ‘access‐rich’ and a much larger number who hold ‘access‐constrained’ portfolios. The literature review and analysis support two broadly applicable conclusions. First, that licensing history shapes access and that limited entry policies continue to influence who benefits from fisheries resources well beyond implementation. Second, that analysing licence holdings suggests business strategies and fishing prospects available to different harvesters and other commercial fisheries participants in a jurisdiction. In response to demand for greater attention to human dimensions and to the perception that indicators are challenging to develop and integrate, we advance conceptual thinking and practical approaches relevant to fisheries research and evaluation.     

Do by‐catch reduction devices in longline fisheries reduce capture of sharks and rays? A global meta‐analysis

By‐catch in marine fisheries, particularly those using pelagic and demersal longlines, is a major driver of declines in abundance of sharks and rays around the world. A wide variety of by‐catch reduction devices (BRDs), that is, modified gears designed to reduce incidental captures of a variety of marine species while maintaining target catch rates, have been proposed, but the extent to which BRDs actually reduce the risk of catching sharks and rays remains unclear. We performed a meta‐analysis of 27 publications that reported the capture of sharks and rays and, in some cases, of targeted teleosts in longline gear deployed with and without BRDs. The risk of shark and ray capture differed between types of BRDs, but only one BRD type, longlines raised off the bottom, reduced by‐catch significantly. Circle hooks did not reduce the risk of capturing sharks and rays but might improve discard survival and are inexpensive, which might make them effective in reducing the detrimental effects of longlining on these species. In addition to being generally ineffective, some devices, such as electropositive and magnetic repellents, are expensive and have inherent construction drawbacks that are likely to make them unsuitable for commercial use. Overall, most BRDs did not affect the likelihood of catching targeted teleosts, but a substantial number of studies did not adequately assess target catch. We identified two poorly studied classes of BRD gear (i.e. raised demersal longlines, and monofilament nylon leaders), which represent promising directions for future research.     

Does the Intensity of Anisakis Infection Affect the Quality of Hake Muscle?

The distribution of Anisakis larvae in fresh caught hake was studied, and the influence of three infection levels of the viscera (low, medium, high) on quality changes of deep frozen muscle was followed over 220 days. Differences in quality were attributed more to the size of the individuals than to the infection degree of the three groups. The removal of belly flaps diminished the risk of consumers’ infection and sensitization as prevalence and intensity was reduced to 75.6 and 5.9%, respectively. Allergens were detected after 220 days frozen storage, which represents a risk for consumers already allergic to Anisakis.     

Does space matter? Optimizing stocking density of Holothuria arguinensis and Holothuria mammata

Stocking density is an important factor affecting growth in aquaculture. The main objectives of this study are to evaluate the effects of different stocking densities on Holothuria arguinensis and Holothuria mammata's growth and determine the optimal density. Four different stocking densities were selected for H. arguinensis (1, 3, 5 and 7 ind/0.2 m²) and three for H. mammata (6, 10 and 12 ind/0.5 m²). Growth (specific growth rate (SGR) and growth rate (GR)), weight change, coefficient of variation and productivity were estimated, additionally the feeding rate on H. mammata. Growth on H. arguinensis decreased as the stocking density increased, showing the higher growth at the stocking density of 1 ind/0.2 m² (SGR: 1.24%/day ± 0.16 and GR: 0.94 g/day ± 0.05), with a 104.65% (±9.98) of weight change. The best H. mammata growth was registered at 10 ind/m² (SGR: 0.56% ± 0.04%/day and GR: 0.48 ± 0.04 g/day) and 25.48% (±1.52) of weight change. H. mammata feeding rate decreased as stocking density increased. Crowding stress could be considered the main factor affecting the sea cucumbers growth and performance on our study. The optimal stocking density for H. arguinensis and H. mammata under tank‐based conditions were established as 1 ind/0.2 m² and 5 ind/0.5 m² respectively. The critic biomass for H. arguinensis (471.65 g/m²) and for H. mammata (988.11 g/m²) were reached during the experiment at the fourth and fifth weeks respectively. Therefore, to ensure and increase growth of these species under tank, their biomass should be maintained under those thresholds.     

Do wild fish species contribute to the transmission of koi herpesvirus to carp in hatchery ponds?

The koi herpesvirus (KHV) has spread worldwide since its discovery in 1998 and causes disease and mortality in koi and common carp populations with a high impact on the carp production industry. Many investigations have been conducted to examine ways of distribution and to identify possible transmission vectors. The answers, however, raise many new questions. In the present study, different wild fish species taken from carp ponds with a history of KHV infection were examined for their susceptibility to the virus. In the tissue of these fish, the virus load was determined and it was tested whether a release of the virus could be induced by stress and the virus then could be transferred to naive carp. Wild fish were gathered from carp ponds during acute outbreaks of virus‐induced mortality in summer and from ponds stocked with carp carrying a latent KHV infection. From these ponds, wild fish were collected during the harvesting process in autumn or spring when the ponds were drained. We found that regardless of season, temperature variation, age and infection status of the carp stock, wild fish from carp ponds and its outlets could be tested positive for the KHV genome using real‐time PCR with a low prevalence and virus load. Furthermore, virus transfer to naive carp was observed after a period of cohabitation. Cyprinid and non‐cyprinid wild fish can therefore be considered as an epidemiological risk for pond carp farms.     

Does the Ricker or Beverton and Holt type of stock-recruitment relationship truly exist?

ABSTRACT:   This study investigated the main causes of population abundance fluctuations. Particularly, attention was paid to whether a density-dependant factor, such as a stock-recruitment relationship (S-R relationship) or a density-independent factor such as an environmental factor, is more important. Using data pertaining to the number of eggs of the Pacific stock mackerel and information about regime shifts and sea surface temperature, the shape of the S-R relationship was discussed and these shapes with the results of simulation trails were compared. Further other historical S-R relationship data were analyzed. The results are as follows: (i) a new mechanism that causes population fluctuations could be proposed, that is, (a) the recruitment is proportional to the spawning stock biomass (SSB) and the relation is expressed by several lines with the same slope, and (b) the shift between the lines occurs due to environmental conditions; and (ii) the density-dependent S-R relationship, which suggests that recruitment decreased due to high density in SSB, proposed by Ricker or Beverton and Holt, would not exist.     

Is serotonin uptake by peripheral tissues sensitive to hypoxia exposure?

Fish Physiology and Biochemistry - In the Gulf toadfish (Opsanus beta), the serotonin (5-HT) transporter (SERT) is highly expressed in the heart, and the heart and gill both demonstrate the...     

Is European catfish a threat to eels in southern France?

• 1. European eel (Anguilla anguilla) is recognized as a critically endangered species in the northern hemisphere. Threats such as overfishing or pollution are well known as risks for eel populations. However, much less is known about the impact of introduced fish on European eels. In particular, introduced large‐bodied predators could become new predators to eels.
• 2. The potential impact of European catfish (Silurus glanis L) on an eel population in the Camargue, southern France was studied using a combination of stable isotope and gut content analyses.
• 3. Only large‐bodied catfish (>500 mm) can consume numerous fish prey. However, catfish mostly consumed crayfish (Procambarus clarkii), these prey items being found in 79% of the guts of the largest individuals. Eel was absent from the dissected catfish guts. A mixing model based on Bayesian inference revealed that catfish diet included only 5% (0–8.5%) of marine sources (both eel and mullet).
• 4. While local economic interests prompted ecological studies to assess whether catfish exerted a new and strong predatory pressure on eel, this study found that European catfish behaved as an opportunistic omnivore, and as such was not a direct threat as a predator on eel populations in the Camargue. Copyright © 2011 John Wiley & Sons, Ltd.

     

How to determine the appropriate mortality in experimental larval rearing?

Survival in larval rearing experiments is difficult to estimate due to accidental losses and periodic sampling. The number of sampled fish can be a large proportion of the stocked ones, making it difficult to calculate the overall survival rate and mortality coefficient as this is based on the initial number. Here, a new method of calculating survival is proposed using the mortality coefficient. When the initial stocking density and sampled and final numbers are known, and assuming that mortality coefficient is constant, the final number of fishes can be represented by the formula N _t = e^−mt (N ₀ − ΣN _Sne ^mdn), where t is rearing period (days), N ₀ indicates initial number, N _t indicates the survival number at t days of rearing, m is the natural mortality coefficient, N _Sn is the sampled number in the nth sampling, and dn is the rearing period until removal of the nth sample. The provisional mortality coefficient is calculated from initial and final stocking numbers. Then values for the natural mortality coefficient are substituted into the formula with successive approximation. The coefficient, which most closely approximates the actual survival, is determined as the best fit natural mortality coefficient. Examples of larval experiments are provided to demonstrate the method and show that survival is often underestimated using traditional methods.