Changes in body condition and fatty acid composition of wild Mediterranean horse mackerel (Trachurus mediterraneus, Steindachner, 1868) associated to sea cage fish farms

A large amount of organic effluents are released annually from coastal fish farming locations primarily in the form of faeces that settle to the seabed, where they become a substantial food source for benthic communities. The inclusion of marine and vegetable oils as sources of lipids in salmon feed has resulted in a fatty acid (FA) composition that differs markedly from marine-derived material, and thus they can be used as an efficient tracer for the distribution of fish farm waste in both sediments and fish. To obtain a better understanding of the flux of organic fish farm waste through the benthic food web, we sampled northern shrimp Pandalus borealis at fish farming and reference locations in 4 regions along the Norwegian coast. Analyses of the FA compositions of muscular tissue demonstrated that shrimp collected within 800 m from fish farms had a higher content of the vegetable-derived FAs 18:2n6 (linoleic acid) and 18:3n3 (α-linolenic acid) and the marine FAs 20:1n9 and 22:1n11, compared with shrimp collected from reference locations. This difference in specific FA contents allowed us to separate shrimp collected at fish farming locations from those collected at reference locations. Our results demonstrate that shrimp within the distribution range of fish farms can incorporate organic fish farm waste into part of their diet, either directly through the consumption of waste feed and faeces or indirectly by feeding on influenced infauna.

Section: Discussionsupporting

confidence: 67%

Tracing fish farm waste in the northern shrimp Pandalus borealis (Krøyer, 1838) using lipid biomarkers

Olsen¹,

Ervik²,

Grahl‐Nielsen³

2012

“…Similarly, Fernandez-Jover et al (2007) highlighted that farm-aggregated Mediterranean horse mackerel Trachurus mediterraneus drastically changed their feeding behaviour while resident around farms, since food pellets averaged 90% of total stomach contents while their non-aggregated counterparts mainly consumed juvenile fish, crustaceans and cephalopods. This was clearly reflected in the FA profile of the fish muscle, which showed significantly increased levels of linoleic and oleic acids and decreased DHA in farm-associated fish (Fig.…”

Section: Fa Profiles Of Adult Fishmentioning

confidence: 99%

“…However, the use of alternative ingredients in aquaculture is prompting further questions about their effects on the environment. Several studies have appeared highlighting that the FA composition of sediments (Colombo et al 1997), wild fish populations (Skog et al 2003, Fernandez-Jover et al 2007, 2009 and other associated fauna-like shrimps (Olsen et al 2009) can be altered as a consequence of food pellets that are not consumed by the cultured fish and are lost from the cages. Therefore, terrestrial FAs have been proposed as biomarkers for the influence and impact of aquaculture on wild fish populations (Skog et al 2003, Fernandez-Jover et al 2007.…”

mentioning

confidence: 99%

“…Wild fish aggregations around coastal sea-cage farms may reach high numbers and biomass (Dempster et al 2002, and changes in the FA profile of this fauna have been detected in both adult and juvenile fish (Skog et al 2003, Fernandez-Jover et al 2007, 2009). This work presents the current status and knowledge of the effects of FAs of terrestrial origin on wild fish communities, focusing on future research efforts and monitoring guidelines for using FAs as biomarkers and also considering the potential effects on fish biology.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Monitoring the influence of marine aquaculture on wild fish communities: benefits and limitations of fatty acid profiles

Fernandez‐Jover¹,

Arechavala-López²,

Martínez-Rubio³

et al. 2011

Fatty acids (FA) have been applied as indicators of the influence of coastal sea-cage fish farming on wild fish communities in several recent scientific publications. Due to the relatively high conservation of FA composition throughout the food web, they are useful for characterizing trophic relationships. The increasing utilization of vegetable or alternative animal oils in the production of aquafeeds results in cultivated fish exhibiting higher levels of terrestrial FAs in their tissues. As previously reported, wild fish ubiquitously aggregate around fish farms as a consequence of the introduction of new habitat and the easy availability of food—fish farms act as enhanced fish aggregation devices (FADs). The influence of food pellets on the composition of wild fish has been detected in recent studies on salmon, sea bass and sea bream aquaculture, with increased levels of linoleic acid (18:2n-6) and a low n-3/n-6 ratio as clear indicators of the consumption of food pellets from the farms. The potential ecological and physiological effects on wild fish are presently unknown. In the present article, guidelines are proposed for the investigation and use of terrestrial FAs to track the effects of coastal aquaculture on wild fish communities and local fisheries, as well as the benefits or limitations of this technique

“…see 'Introduction') have shown the importance of marine fish farms as attractors of wild fish, and based on a variety of techniques (e.g. lipid analysis, Fernandez-Jover et al 2007) to identify wild fish, at least one of the reasons for this attraction is to feed on fish wastes. However, estimating the scale of the trophic transfer of fish wastes to wild fish is very difficult experimentally as wild fish exist in a relatively open system.…”

mentioning

confidence: 99%

MERAMOD: predicting the deposition and benthic impact of aquaculture in the eastern Mediterranean Sea

Cromey¹,

Thetmeyer²,

Lampadariou³

et al. 2012

A model composed of coupled particle tracking and benthic response modules was developed for predicting waste solids flux and benthic impacts of gilthead sea bream Sparus aurata L. and sea bass Dicentrarchus labrax L. aquaculture. The model was tested at 6 sites with different hydrodynamics, bathymetries and biomasses in the Aegean and Ionian seas, eastern Mediterranean Sea, and sediment trap flux and benthic impact indicators were observed. Seven sediment trap validation studies were conducted that varied in design with traps deployed either on the seabed, attached to nets or suspended in the water column. Model predictions of flux to traps spaced 5 m apart up to 50 m from the cages over a 13 d period were significant (R 2 = 0.61, n = 57, p ≤ 0.05). However, the model could not predict adequately the flux to traps spaced 2 m apart in the high-flux zone underneath cages where variability between trap observations was high. In this high-flux zone underneath cages, the averaged model flux predictions resulted in a performance of ± 49%. Statistically significant relationships were established at 4 sites between modelled flux and either benthic fauna impact indicator species (S), abundance (A), A/S ratio, Shannon-Wiener index or biomass fractionation index (BFI), (R 2 = 0.82, 0.60, 0.57, 0.67 and 0.48, respectively; n = 24, p ≤ 0.05). Two other sites, which did not exhibit an abundance peak in enriched zones, did not fit these relationships. Using relative abundance of taxonomic groups, a modelled flux of 4.1 g m −2 d −1 was determined to be a useful boundary; on either side of this boundary, clear trends occurred in pollutant tolerant and intolerant species.