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- The effect of tank cover on welfare of farmed Nile tilapiaPublication . Saraiva, João L.; Nogueirinha, Margarida; Teodósio, Rita; Aragão, Cláudia; Engrola, Sofia; Arechavala Lopez, PabloWelfare in aquaculture is a pressing topic. One of the main measures to improve the life of farmed fish is implementing environmental enrichment, which can include the addition of structural covers to rearing tanks. Here we test the effects of tank covers (fully covered, 50 % covered and uncovered) in an all-male population (N = 75 tagged individuals: 5 individuals per tank, 5 tanks per treatment) of farmed Nile tilapia using behavioural and physiological welfare indicators. Video recordings were performed over 21 days to evaluate overall swimming (swim bursts, freezing on the bottom or hovering in the water column) and aggression events (bites and chases). At the end of the experiment, blood was collected to assess circulating cortisol. Results showed a clearly lower welfare in the partially covered tanks regarding behavioural and physiological variables. The present study highlights the need to correctly study 1) the ethology of the farmed species and 2) the enrichment strategy to be implemented, before any measure is taken. While environmental enrichment is undoubtedly a much needed area of research and a promising solution to improve the welfare of farmed fish, a proper ethological assessment must be made a priori to avoid detrimental effects of poorly devised approaches.
- A global assessment of welfare in farmed fishes: the FishEthoBasePublication . Saraiva, João; Arechavala Lopez, Pablo; Castanheira, Maria Filipa; Volstorf, Jenny; Heinzpeter Studer, BilloFish welfare is an essential issue that needs to be tackled by the aquaculture industry. In order to address it, studies have been limited to a small number of species and the information is generally scattered. In order to have a consistent overview of the welfare of farmed fishes, we present the FishEthoBase, an open-access database that ultimately aims to provide information on the welfare of all fish species currently farmed worldwide. Presently with 41 species, this database is directed to all stakeholders in the field and targets not only to bridge the gaps between them but also to provide scientific information to improve the welfare of fish. The current text explains the database and presents an analysis of the welfare scores of 41 species, suggesting that (i) the general welfare state of farmed fishes is poor, (ii) there is some potential for improvement and (iii) this potential is related to research on species’ needs, but (iv) there are many remaining knowledge gaps and (v) current fish farming technologies do not seem to fully address welfare issues. The existence of a framework, such as the FishEthoBase, is proposed as fundamental to the design of strategies that improve the welfare of farmed fish.
- Accelerometry of seabream in a sea-cage: is acceleration a good proxy for activity?Publication . Palstra, Arjan P.; Arechavala Lopez, Pablo; Xue, Yuanxu; Roque, AnaActivity assessment of individual fish in a sea-cage could provide valuable insights into the behavior, but also physiological well-being and resilience, of the fish population in the cage. Acceleration can be monitored continuously with internal acoustic transmitter tags and is generally applied as a real-time proxy for activity. The objective of this study was to investigate the activity patterns of Gilthead seabream (Sparus aurata) by transmitter tags in a sea-cage and analyze correlations with water temperature, fish size and tissue weights. Experimental fish (N = 300) were transferred to an experimental sea-cage of which thirty fish (Standard Length SL = 18.3 1.7 cm; Body Weight BW = 174 39 g) were implanted with accelerometer tags. Accelerations were monitored for a period of 6 weeks (Nov.–Dec.) and were analyzed over the 6 weeks and 24 h of the day. At the end of the experimental period, tagged fish were again measured, weighed and dissected for tissue and filet weights, and correlations with accelerations were analyzed. Daily rhythms in accelerations under the experimental conditions were characterized by more active periods from 6 to 14 h and 18 to 0 h and less active periods from 0 to 6 h and 14 to 18 h. This W-shaped pattern remained over the experimental weeks, even with diurnal accelerations decreasing which was correlated to the dropping temperature. The increase in activity was not during, but just before feeding indicating food-anticipatory activity. Activity patterning can be useful for timing feeding events at the start of active periods, in this study between 6 and 11 h, and between 18 and 22 h. Acceleration was negatively correlated to heart and mesenteric fat mass, which was the exact contrary of our expectations for sustainedly swimming seabream. These results suggest that acceleration is a proxy for unsteady swimming activity only and research is required into the accelerations occurring during sustained swimming of seabream at various speeds.
- Welfare of fish—no longer the elephant in the roomPublication . Saraiva, João L.; Arechavala Lopez, PabloThe concept of fish welfare is fairly recent and was overlooked for many years, based on a popular misconception that fish were “stupid” creatures devoid of any kind of sentience or mental capability [...] (excerto da primeira página).
- Environmental enrichment in fish aquaculture: a review of fundamental and practical aspectsPublication . Arechavala Lopez, Pablo; Cabrera‐Álvarez, Maria J.; Maia, CM; Saraiva, JoãoEnvironmental enrichment (EE) can improve the welfare of captive fish. Its objective is to provide new sensorial and motor stimulation in order to help meet their behavioural, physiological, morphological and psychological needs, whilst reducing stress and frequency of abnormal behaviours. In fish farms, rearing environments are usually designed from a human perspective and based on economic requirements, mainly for practical reasons for the farmer, with little consideration for animal welfare. Throughout aquaculture production cycles, many farming operations can be stressful for fish, and EE may not only help them cope with these stressful events but also improve their overall welfare. In recent years, increasing interest on the effects of EE in captive fish has focussed mainly on structural enrichment. However, there are many other enrichment strategies that merit attention (e.g. sensorial, occupational, social and dietary enrichment) and which may be of interest for fish farming. Here, we review in depth the existing literature on EE and its effects on the welfare of a wide range of farmed fish species, discussing the feasibility and potential applications of different EE strategies to promote fish welfare at a commercial scale. We also present a practical framework to address the design, validation and implementation of EE by the aquaculture industry, taking in consideration the technical challenges of providing enrichment for farmed fish.
- Behaviour and body patterns of Octopus vulgaris facing a baited trap: first-capture assessmentPublication . Dominguez Lopez, Marta; Follana-Berná, Guillermo; Arechavala Lopez, PabloThis study highlights for the first time individual differences in ethology and vulnerability of Octopus vulgaris (i.e. body postures, movements and skin displays) facing passive baited traps. Common octopus exposed to a baited trap during three consecutive first-capture tests exhibited diverse behavioural and body pattern sequences resembling when the octopus searches for and hunts its wild prey. Overall, they first visually recognized new objects or potential preys and rapidly moved out of the den, exploring, grabbing and approaching the trap with the arms (chemotactile exploration), and capturing the bait with the arms and feeding on top over long periods inside the trap. Simultaneously, O. vulgaris displayed diverse skin textural and chromatic signs, the regular pattern being the most frequent and long-lasting, followed by broad mottle, passing cloud and dark patterns. All individuals (n=8) caught the bait at least once, although only five octopuses (62.5%) entered the trap in all three tests. In addition, high variability among individuals was observed regarding behaviour and body patterns during the first-capture tests, which might evidence different individual temperaments or life-history traits. Differences in behavioural responses at individual level might have population consequences due to fisheries-induced selection, although there is a high necessity to assess how behavioural traits might play an important role in life-history traits of this species harvested by small-scale trap fisheries.
- Effects of structural environmental enrichment on welfare of juvenile seabream (Sparus aurata)Publication . Arechavala Lopez, Pablo; Diaz-Gil, C.; Saraiva, João L.; Moranta, D.; Castanheira, Maria Filipa; Nuñez-Velázquez, S.; Ledesma-Corvi, S.; Mora-Ruiz, M.R.; Grau, A.Current production systems of finfish aquaculture, and in particular intensive farming systems, can cause welfare problems leading not only to poor condition of the fish but also to a decrease in product quality. Adding structural environmental enrichment (EE) to bare rearing environments may improve the welfare of certain cultured fish. In this study we experimentally demonstrate the positive effects of adding structural EE on rearing environments of juvenile seabream (Sparus aurata). Fish maintained for 35 days with EE showed less aggression and interactions with the net pen, and lower erosion of pectoral and caudal fins, compared to fish kept in bare conditions (non-enriched, NE). In addition, EE modified the horizontal distribution of fish in the experimental cage, increasing the use of the inner areas. Non-significant effects of EE were observed on fish body condition and growth, and on brain monoamines levels and mortality. Nevertheless, this work highlights the potential use of structural EE to improve welfare of juvenile seabream, which might be feasible to apply at larger-commercial scale.