| 1. |
- Andersson, Marica, et al.
(författare)
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Increased noise levels cause behavioural and distributional changes in Atlantic cod and saithe in a large public aquarium—A case study
- 2023
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Ingår i: Aquaculture, Fish and Fisheries. - : John Wiley & Sons. - 2693-8847.
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Investigating the effects of underwater noise on aquatic animals is a research field that is receiving rapidly increasing attention. Despite this, surprisingly few studies have addressed the potential impacts of noise in a marine animal husbandry setting. In this regard, the behaviour of fish in public aquariums can be used as an indicator of well-being, and noise is known to cause behavioural changes. This case study investigates the behaviour of cod (Gadus morhua) and saithe (Pollachius virens) in a large public aquarium when exposed to increased noise levels originating from an aquarium renovation carried out by construction divers. Swimming behaviour, group formation and vertical distribution, along with yawning and scratching frequencies of the fish, were analysed from video recordings made before, during and after the exposure to increased noise levels. The same parameters were also analysed to evaluate potential effects of the presence of divers when not making renovation noise, compared to fish behaviour prior to the renovation. There was a slight change in the depth distribution of both species and a decrease in the number of scratches in cod due to the presence of divers that were not making renovation noise. In the presence of construction noises in the tank, however, both cod and saithe showed a wider array of behavioural changes, including increased swimming speed, changes in depth distribution and increased yawning frequencies. The results from this case study demonstrate that an underwater renovation with increased noise levels impacts fish behaviour and suggests that underwater noise should be considered during the management of aquatic environments, including public aquaria.
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| 2. |
- Losee, James
(författare)
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Restrictions on leader length in an in-river sport fishery reduce catch of threatened wild chinook salmon Oncorhynchus tshawytscha and increase harvest of hatchery origin chinook
- 2022
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Ingår i: Aquaculture, fish and fisheries. - : Wiley. - 2693-8847. ; 2, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- To achieve conservation and harvest objectives associated with Chinook Salmon, fisheries managers have relied on mark-selective and anti-snagging rules in freshwater whereby anglers are required to release wild Chinook and fish hooked in anatomical locations other than the head and mouth. However, in some cases these regulations have resulted in increased mortalities due to the number of fish (hatchery and wild) that require release. Regulations effective at increasing the number of fish hooked in the mouth have the potential to decrease total encounters (number of fish caught) of both hatchery and wild fish while increasing the total number of fish harvested; however, this has not been tested. A roving creel survey and a test fishery were used to describe the effect leader length and bait under a bobber has on catch rate and hooking location and simulate how a variety of restrictions on gear type would affect catch and harvest on wild and hatchery origin Chinook salmon. Results indicate that a 6-foot leader length restriction would result in the highest catch of hatchery fish harvested and reduce exploitation rate on wild fish by greater than 20%. Regulations limiting leader length to 3 feet are expected to result in the greatest reduction (75.7%) to total encounters on wild fish; however, this method was unpopular and resulted in few hatchery fish harvested. The use of bait suspended under a bobber resulted in intermediate results with a reduction of 60.0% to catch of wild Chinook and the smallest number hooked outside the mouth (0/30). These results provide the first evaluation of the effect of leader length in a mark-selective hook and line fishery and suggest that a 6-foot leader length restriction would be expected to reduce encounters on wild Chinook, increase harvest of hatchery fish and extend the fishing season.
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| 3. |
- Lundh, Torbjörn
(författare)
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Integration of Nile tilapia (Oreochromis niloticus) and vegetables (Amaranthus hybridus and Brassica rapa pekinensis) for improved production, water use efficiency and nutrient recycling
- 2022
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Ingår i: Aquaculture, fish and fisheries. - : Wiley. - 2693-8847. ; 2, s. 493-506
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable agriculture intensification is an urgent challenge in developing countries including Tanzania. One potential solution is to adopt farming systems that increase farm production by optimizing resource use efficiency, and integrated aquaculture system, which involves farming of fish and crops, is an example of such systems. This study investigated the impact of Integrated agriculture and aquaculture (IAA) farming on water use efficiency, fish and vegetable production and overall system profitability, and how these parameters are affected by fish stocking densities. Oreochromis niloticus (2.5 g average initial weight) were cultured at low stocking density (five fish m−3, LSD), medium stocking density (eight fish m−3, MSD), and high stocking density (12 fish m−3, HSD) for 205 days. Brassica rapa pekinensis and Amaranthus hybridus cultivated adjacent to the fish tanks were irrigated with; (i) fish tank water, without any fertilizer inputs; (ii) fish tank water, partially fertilized; (iii) tap water, fully fertilized (farmers’ practice); and (iv) tap water without any fertilizer inputs. Although the use of tank water from the high fish stocking density resulted in significantly higher vegetable yield, high fish stocking resulted in lower fish growth, profitability and water use efficiency compared to the other fish stocking densities, probably because of low survival rates (28%) at high stocking densities. The integration of fish at a medium stocking density with vegetables resulted in significantly higher net income than when fish and vegetables were grown separately.
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| 4. |
- Staveley, Thomas A. B., et al.
(författare)
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Sea trout (Salmo trutta) activity and movement patterns in response to environmental cues in a fjord system
- 2024
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Ingår i: Aquaculture, fish and fisheries. - : John Wiley & Sons. - 2693-8847. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- As a predatory fish that migrates between freshwater and marine environments, the sea trout (Salmo trutta) is important in linking these systems. This study investigated movement patterns of sea trout in a coastal fjord at the Swedish Skagerrak region from August 2018 to January 2019, using acoustic telemetry, while assessing these against environmental variables across different spatial and temporal scales. Six acoustic receivers were deployed in the fjord and a river, which flows into the upper reaches of the fjord, with the aim of detecting 20 sea trout that had been tagged with acoustic transmitters. Sea surface temperature and winds (east-west) affected movement patterns of the sea trout the most, while changes in atmospheric pressure were also important, but to a lesser extent. Sea surface temperature and atmospheric pressure both had a positive relationship with the number of detections, whereas stronger winds from the east (i.e. from land) resulted in more detections than stronger winds from the west (i.e. from the ocean). In addition, interesting diel (day-night) movement patterns were observed for some fish. A significant positive correlation was also discovered between the weight of the fish and the number of detections. This study offers insight in movements of sea trout that use coastal habitats and how environmental conditions can affect movement patterns in a fjord system. To further our understanding of sea trout movement patterns and connectivity, tracking from river, through fjord, out to sea and at a longer time scale with more variation in fish size would be valuable to understand more about the complex movement dynamics of this important species.
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