Management actions in relation to the controversy about salmon lice infections in fish farms as a hazard to wild salmonid populations

Risk analysis provides a logical strategy for the identification of hazards in an area of concern leading to their management. This approach has rarely been used for research studies on the possible links between salmon lice in fish farms and variations in wild salmonid populations. Although correlation has been found between some data sets, a series of international meetings of experts has not been able to establish cause–effect relationships between lice on farms and the current low level of salmonid stocks in Europe and eastern Canada. Research in this area is currently in progress in western Canada. Views on the meaning of the correlations found have become highly polarized in both the scientific and non‐scientific communities, with the same data often being interpreted in different ways. Farm lice levels are being managed by industry codes and by official strategies in Europe, but these programmes have not so far resulted in associated benefit to the size of wild salmonid stocks. The large array of factors that cause variations in both the size of fish stocks and the level of fish diseases is frequently overlooked. Using a risk analysis approach, the key contributory factors may be identified and appropriate remedial management actions designed to meet achievable objectives. Regular assessment of the effectiveness of the measures introduced would then be possible.     

Regulatory costs on U.S. salmonid farms

The economic effects of the implementation of regulations on aquaculture farms in the United States, while of concern, are not well understood. A national survey was conducted of salmonid (trout and salmon) farms in 17 states of the United States to measure on‐farm regulatory costs and to identify which regulations were the most costly to this industry segment. The response rate was 63%, with a coverage rate of 94.5% of the U.S. production of salmonids. The regulatory system resulted in increased national on‐farm costs of $16.1 million/year, lost markets with a sales value of $7.1 million/year, lost production of $5.3 million/year, and thwarted expansion attempts estimated at $40.1 million/year. Mean farm regulatory costs were $150,506/farm annually, or $2.71/kg; lost markets with annual sales values of $66,274/farm; annual lost production of $49,064/farm; and an annual value of thwarted expansion attempts estimated at $375,459/farm. Smaller‐scale farms were affected to a disproportionately greater negative extent than larger‐scale farms. Per‐farm regulatory costs were, on average, greater for foodfish producers than for producers selling to recreational markets, but per‐kg regulatory costs were greater for those selling to recreational compared to foodfish markets. Regulatory costs constituted 12% of total production and marketing costs on U.S. salmonid farms. The greatest regulatory costs were found to be effluent discharge regulations. The majority of regulatory costs were fixed costs, but regulatory barriers to expansion precluded compensatory adjustments to the business in spite of growing demand for salmonid products. Results of this study show that the on‐farm regulatory cost burden is substantial and has negatively affected the U.S. salmonid industry's ability to respond to strong demand for U.S. farm‐raised salmonid products. Results also suggest that the regulatory system has contributed to the decline in the number of U.S. salmonid farms. While regulations will necessarily have some degree of cost to farms, the magnitude of the on‐farm regulatory cost burden on U.S. salmonid farms calls for concerted efforts to identify and implement innovative regulatory monitoring and compliance frameworks that reduce the on‐farm regulatory cost burden.     

Movements of fur seals following relocation from fish farms

• 1. The movement patterns of Australian and New Zealand fur seals trapped on salmon farms in south‐east Tasmania and relocated hundreds of kilometres away, were monitored using satellite telemetry. Australian fur seals released 470 km away by sea returned to farms after an average of 8.5±4.4 days (n=9 trips) and those released at 140 km returned after 3.2±0.8 days (n=4 trips). New Zealand fur seals (n=5 trips) averaged a return time of 6.8±1.2 days from 300 km.
• 2. When in south‐east Tasmania, both seal species undertook short trips to sea (mean 2.6 days) from haul‐out sites (minimum distance from farms 21 km) with 33% (1.8 days) of this time spent within 5 km of farms. Mean haul‐out duration was 1.1 days.
• 3. In summer, Australian fur seals repeatedly travelled between northern Bass Strait islands and southern Tasmanian waters following the Tasmanian east coast. Seals did not visit farms during this time.
• 4. Southern Tasmanian waters are important foraging grounds for fur seals and potential exists for a substantial number of seals to visit nearby fish farms. Farms provide predictable food resources from penned and escaped salmon, and wild fish attracted to the area.
• 5. Australian fur seals trapped at Tasmanian salmon farms regularly visited breeding colonies on islands in Victoria.

Copyright © 2008 John Wiley & Sons, Ltd.     

Forecasting weekly salmon prices: Risk management in fish farming

Abstract

Production of farmed salmon has increased substantially during the last decade. Most of the salmon production is sold spot, resulting in large price fluctuations both for the producer and for the exporter. No derivative markets exist; consequently, no one can hedge prices. If prices could be forecasted within reasonable confidence bounds, risk would be reduced. This study used six easily applicable procedures to forecast weekly producer prices for salmon. The procedures tested were Classical Additive Decomposition (CAD), Holt Winters Exponential Smoothing (HW), Auto Regressive Moving Average (ARMA), Vector Auto Regression (VAR) and two different naïve models: post‐sample predictive accuracy was evaluated. Results indicated that the CAD model forecasted the direction of price movements best, whereas the VAR model performed best according to accuracy measures.     

Tracking escaped Atlantic cod (Gadus morhua L.) aggregated around Norwegian farms: Considerations for management strategies

To examine site fidelity and potential for ecosystem impacts, 20 escapee cod (Gadus morhua L.) from fjord‐based cod farms were tagged with acoustic transmitters, released in the vicinity of the same farm, and their subsequent behaviour and survival monitored using a fixed array of acoustic receivers. Most individuals demonstrated high fidelity to their farm where tagged, and this increased during the polar night. Only five individuals (25%) were occasionally detected at another farm (4 km distance), and only three cod (15%) migrated out of the fjord during the 6‐month study period. Vertical movements were consistently greater in the hours around noon than at night, a behaviour inconsistent with that observed for wild fish. A high mortality rate (40%) was observed during the first 4 months post‐release, and actual mortality may have been even higher, limiting the potential for negative ecosystem effects from cod escapees. Findings from this study are used to discuss the development of recapture strategies for minimising potential impacts from cod escapees to ensure sustainable farming activity.     

Seasonal increase in sea temperature triggers pancreas disease outbreaks in Norwegian salmon farms

Pancreas disease (PD) is a viral disease causing negative impacts on economy of salmon farms and fish welfare. Its transmission route is horizontal, and water transport by ocean currents is an important factor for transmission. In this study, the effect of temperature changes on PD dynamics in the field has been analysed for the first time. To identify the potential time of exposure to the virus causing PD, a hydrodynamic current model was used. A cohort of salmon was assumed to be infected the month it was exposed to virus from other infective cohorts by estimated water contact. The number of months from exposure to outbreak defined the incubation period, which was used in this investigation to explore the relationship between temperature changes and PD dynamics. The time of outbreak was identified by peak in mortality based on monthly records from active sites. Survival analysis demonstrated that cohorts exposed to virus at decreasing sea temperature had a significantly longer incubation period than cohorts infected when the sea temperature was increasing. Hydrodynamic models can provide information on the risk of being exposed to pathogens from neighbouring farms. With the knowledge of temperature‐dependent outbreak probability, the farmers can emphasize prophylactic management, avoid stressful operations until the sea temperature is decreasing and consider removal of cohorts at risk, if possible.     

Impact of Caligus treatments on unit costs of heterogeneous salmon farms in Chile

We measure the impact that sanitary treatments that control ectoparasite Caligus rogercresseyi abundance have on unit production costs of Salmo salar farms in Chile. We follow complete production cycles for a sample of farms between 2009 and 2015. We estimate a simultaneous salmon biomass growth and Caligus abundance model. The statistical analysis determines the effect of antiparasitic treatments, location of farms, environmental conditions and Caligus abundance on the salmon growth profile. Using outside cost information, we simulate how unit production costs vary by treatment and farm characteristics. Our results suggest that unit production costs increase on average by $1.4?US/kg with Caligus and treatments. Treatment costs are compensated by higher harvesting levels, and unit production costs are invariant to the situation without treatment. All estimated effects differ depending on farm’s environmental and spatial conditions, suggesting that the design of cost-effective intervention calls for discriminatory regulation under heterogeneous conditions.     

Tank size and fish management history matters in experimental design

To investigate the questions: (1) does tank size affect fish performance; (2) does tank size prior to an experiment affect later fish performance and (3) how does performance in experimental tanks compare with rearing in industry‐scale cages, Atlantic salmon smolts were acclimatized to 190, 3 or 0.9 m³ tanks (Phase 1; 1.5 months) before redistributed to Phase 2 for 5 months. Question 1: fish in 190 m³ tank were redistributed to 0.9 m³ (190 m³ → 0.9 m³), 3 m³ (190 m³ → 3 m³), or 103 m³ (190 m³ → 103 m³) tanks. Question 2: fish in 0.9 m³ tanks were redistributed to 3 m³ tanks (0.9 m³ → 3 m³), and compared to fish from 190 m³ tank (190 m³ → 3 m³). Question 3: fish were placed directly in 3 m³ tanks, not moved (3 m³ → 3 m³), and compared to reference sea cages. Phase 2 mortality: 190 m³ → 0.9 m³ (46%), 190 m³ → 3 m³ (29%), 190 m³ → 103 m³ (19%), 3 m³ → 3 m³ and 0.9 m³ → 3 m³ (<5%). Most mortality happened shortly after transfer. Our study suggests tank size dependent performance, based on growth and feed intake that increased with tank size. 190 m³ → 103 m³ fish were more active than 190 m³ → 0.9 m³ and 190 m³ → 3 m³ fish. 190 m³ → 103 m³ tanks had lowest relative variance. Previous tank scale history affected survival, since 0.9 m³ → 3 m³ fish showed higher survival than 190 m³ → 3 m³ fish. However, previous scale history did not affect growth rate, feed intake or somatic indexes. Fish performance in 3 m³ → 3 m³ tanks did not differ from the reference sea cages. However, fish in 103 m³ tanks performed better than reference cages, suggesting potential for improved commercial production. This study demonstrates that management practices can influence fish performance and should be taken into account when designing experiments.     

基于RFID技术的亲鱼养殖管理系统设计与实现

基于无线射频识别(RFID)技术建立亲鱼养殖管理系统能够大大减少人工工作量,并对亲鱼养殖全程实现可靠精细化的管理、跟踪和追溯。测试分析结果表明,天线直径分别为25 cm和40 cm两种规格的RFID抄网读写器,能够在平均距离16.41～22.82 cm范围内,稳定地读写亲鱼皮下肌肉内的玻璃标签,在后台软件系统的支持下,能够实现对亲鱼养殖全程的有效管理、跟踪和追溯。     

Discrimination of Norwegian farmed, ranched and wild-origin Atlantic salmon, Salmo salar L., by image processing

Abstract  A method of distinguishing between farmed, ranched and wild-origin Atlantic salmon, Salmo salar L., using scale morphology is proposed. Circuli spacing and scale texture data, as expressed as a Fourier transform of transmission luminescent patterns. were extracted by image processing. Spacing patterns and texture features were most distinct for wild salmon compared with the other two groups. Three-group quadratic discriminant function models were developed using different combinations of data types. The most efficient model to separate the three groups had a classification efficiency of 74%. When models were simplified to two groups, farmed and wild, efficiency increased to 90%, thus reflecting the feature overlap between farmed and ranched groups. The method may be a useful tool for more objective and efficient classification of wild versus husbandry-origin salmon. However, it should be stressed that farmed salmon that escape at the smolt stage are still problematic.     

Dispersal of large farmed Atlantic salmon, Salmo salar, from simulated escapes at fish farms in Norway and Scotland

Abstract  Individually tagged farmed Atlantic salmon, Salmo salar L., were released from fish farms in simulated escapes in Scotland ( n  =   678) and Norway ( n  =   597) to compare migratory behaviour and dispersal. Large fish (510–870 mm fork length) were released to simulate the escape of aquaculture growers. Fish were released in spring and all recaptures of tagged fish were reported during summer and autumn of the year of release. Recapture rates were respectively 7.0 and 0.6% of the salmon released in Norway and Scotland, indicating a higher mortality or a lower exploitation or reporting rate for Scottish fish. Recaptures of Norwegian fish were all from Norway and mostly within 150 km of the release site; 64% were taken by anglers in fresh water. By contrast, the three salmon recaptured from the release in Scotland were reported from Norway (Hardangerfjord and Lofoten) and western Sweden (River Göta); two detached tags were found on beaches in Scotland north of the release site. These findings establish the capacity for long distance dispersal among escapees from aquaculture facilities and suggest a net easterly bias in long distance dispersal of salmon escaping from Scottish fish farms.     

Interaction between monk seals Monachus monachus (Hermann, 1779) and marine fish farms in the Turkish Aegean and management of the problem

Mediterranean monk seals Monachus monachus attacked fish on 11 marine fish farms in the Turkish Aegean between 1992 and 2000. There were 40 attacks on fish farms where gilthead sea bream Sparus auratus and European sea bass Dicentrarchus labrax were raised in holding cages. Single seals usually attacked cages at night, regardless of the size of fish in the cages. The seals damaged both holding nets of the cages and fish and, on most occasions, fish escaped as a result of the attacks. With the exception of only one facility, all fish farms attacked by monk seals were concentrated on the large peninsulas including Karaburun and Bodrum Peninsulas, and the number of seal attacks was higher during the winter months. A direct intervention to deter seals such as the use of lights, feeding with pesticide‐injected fish, noise generation, warning and direct shots with rifles and physical exclusion of seals from holding cages by installing antipredator nets were applied to prevent or reduce seal attacks. Our study shows that deterrents such as lights and warning shots were not effective in preventing monk seal attacks. However, both curtain‐ and bag‐type antipredator nets were found to be effective.     

Particle size distribution of wastes from freshwater fish farms

Waste water treatment on freshwater fish farms is problematic as waste material and water flows can vary greatly on a daily basis, and, in terms of effluent standards, fish farm effluent represents a dilute waste water output. A study was undertaken to investigate in detail the nature of the waste outputs under field conditions. Waste water samples were split by meshes into the following size ranges: >200μm, 200-100μm, 100-60μm, 60-30μm and <30μm. Waste water quality parameters, suspended solids (SS), biochemical oxygen demand (BOD₅) and total phosphorus (TP) were examined for each size range at two freshwater fish farm sites in Scotland, as part of a wider investigation into waste water quality of aquaculture operations. Results indicated that during periods of peak waste output i.e. tank cleaning, approximately 80% of BOD₅ and SS was present in a particle size range of 100-60μm, but only 66% of TP transport occurred in this size range. At other times, low levels (≤40%) of entrapment of wastes by the chosen meshes was observed, suggesting a reversion to predominantly dissolved material transport. Compared against a larger data set of outflow concentrations obtained from another section of the study, maximum removal rates of 46%, 48% and 30% for BOD₅, SS and TP respectively were determined. The implications for waste water treatment at fish farms are discussed.     

Relationship between feed input and sediment quality of the fish cage farms

ABSTRACT: A study was conducted to examine the variation in fish farm sediment quality with varying organic carbon input in the form of feed. In order to elucidate the seasonal variation in farm sediment quality, relation between seasonal organic carbon input, temperature and sediment quality was studied. The sediment ignition loss, redox potential and acid volatile sulfide sulfur (AVS-S) content showed a correlation with annual organic carbon input. The seasonal AVS-S content showed a significant correlation with the seasonal organic carbon input as well as temperature. Multiple regression analysis revealed that both of these factors explicated 80% of the seasonal variation in AVS-S content. Although redox conditions of the sediment could also be correlated with both the organic carbon input and temperature, the latter seemed to have a greater control. Thus, the farm sediment quality could be directly related to the annual organic carbon input to the fish farm under similar hydrographic conditions. Acid volatile sulfide sulfur content exhibited a significant correlation with both the annual as well as the seasonal organic carbon input. Therefore, AVS-S content proved to be a fairly simple and better indicator for monitoring the fish farm environment for effective farm management and sustainable aquaculture. Importance of size of pellets as a factor affecting the feed input-sediment quality relation is also demonstrated in the present study.     

On the drivers of cost changes in the Norwegian salmon aquaculture sector: a decomposition of a flexible cost function from 2001 to 2014

Abstract

Since 2005, Norwegian salmon farmers have experienced increasing unit costs, contrasting pre-2005 trends characterized by innovations, rapid productivity growth, and diminishing unit costs. This article investigates these cost changes using a panel of salmon producers. The drivers behind cost changes in the industry are identified for the period of 2001–2014 using a flexible cost function. In particular, it is explored how cost changes can be attributable to scale economies, negative productivity shocks, production expansion, and input prices. The results indicate that cost increases in the sector are affected by external factors out of the control of individual firms such as input prices and environmental conditions like sea lice.     

Mitigating fur seal interactions: relocation from Tasmanian aquaculture farms

• 1. At Tasmanian salmon aquaculture farms, fur seals were trapped and relocated to reduce interactions with stock, operations and equipment. From 1990 to 2005, 4517 relocations of 1124 seals were undertaken, peaking at 1203 relocations in 2003.
• 2. Of the relocations, 56% were recaptured seals. Most seals had less than 10 captures (46%), with 3% trapped more than 20 times.
• 3. Relocations were mostly seasonal, occurring in the austral winter and spring with a peak in August.
• 4. Seal recapture intervals were highly variable, ranging from days to years. Within the same year, recapture intervals per seal ranged from 4 to 258 days, mean 36 days.
• 5. Australian fur seals were trapped more frequently than New Zealand fur seals. The first trapped New Zealand fur seal was identified in 2000.
• 6. Relocation provides short‐term relief from seal interactions but does not mitigate the interaction problem in the longer term.
• 7. The core of the seal interaction problem is the current inability to exclude seals from pens and fish stock. Salmon farms are providing a predictable, accessible food source for seals.

Copyright © 2008 John Wiley & Sons, Ltd.     

Spatial and temporal variations of sediment quality in and around fish cage farms: A case study of aquaculture in the Seto Inland Sea, Japan

ABSTRACT: Fish cage farming generates large amounts of organic waste in the form of unconsumed feed and fecal matter, resulting in sediment deterioration and a threat to its own sustainability. Field studies analysed the scale of the impact of fish cage farming on sediment quality, variability of impact and spread of sediment enrichment in the vicinity of a fish farm. Two fish culture sites near the Fukuyama area of the Seto Inland Sea of Japan were chosen for the study. There was a significant difference between the quality of the sediment in aquaculture and non-aquaculture areas. The sediment underlying the fish cage farms was found to be extremely reducing, acidic and sulfidic. Sediment ignition loss did not vary markedly with the season. However, the redox potential and acid volatile sulfide content of aquaculture areas did show some seasonal variation. Sediment encircling a 165 m radius from the center of a farm in Yokota was judged as organically enriched by fish farming. A variation in sediment quality within the two sites and also within the stations was observed. Based on sediment quality, the stations could be categorized as less affected, highly affected or moderately affected.     

IS THERE A FUTURE FOR SALMON FUTURES? AN ANALYSIS OF THE PROSPECTS OF A POTENTIAL FUTURES MARKET FOR SALMON

Many futures contracts for food commodities have been introduced; however, most of them have been withdrawn from the market due to poor liquidity. In this article, various known success factors for futures contracts are discussed with regards to a proposed futures contract for salmon. Criteria from the literature are used. The principal conclusion is that a salmon contract might have difficulty surviving for a long period of time. Alternative means to manage the price risk in the salmon industry are proposed.     

DNA barcoding reveals blend of silver catfish Rhamdia species from fish farms in Southern Brazil

Rhamdia quelen is the most produced native freshwater fish in fish farms in South Brazil. Until recently, Rhamdia branneri and Rhamdia voulezi were synonyms of R. quelen, and all the species are commercialized as silver catfish (locally called jundiá or bagre sapo) by the aquaculture industry. In fact, because these species are morphologically very similar, interspecific crosses easily might occur in fish farming. We employed standard DNA barcoding to identify jundiá molecular operational taxonomic units (MOTUs) in fish cultivated and commercialized in the industry and in possible escapees in the natural environment in southern Brazil. We analysed 48 individuals from six fish farms and 48 individuals from three rivers (Uruguay, Benedito Novo and Itapocu Rivers) using the mitochondrial cytochrome oxidase subunit I (COI). Four MOTUs were identified based on the estimated optimum threshold (OT = 0.77), and these MOTUs were concordant with Bayesian Inferece (BI) and Neighbour‐Joining (NJ) trees. Our results support the existence of at least three species in our dataset: R. branneri, R. voulezi, and R. quelen 1 and R. quelen 2. The interspecific genetic divergence ranged from 1.1% to 5.1% (mean = 3.5%), and the intraspecific distance ranged from 0% to 1.4% (mean = 0.24%). The presence of cultivated fish in the Uruguay and Benedito Novo Rivers provides evidence of genetic contamination in native populations. These results show the need to regulate aquaculture activities and to characterize the species and commercial lineages of silver catfish that are cultivated in South Brazil.