Mortality of Baltic sea trout (<i>Salmo trutta</i>) after release from gillnets

Veneranta, Lari; Pakarinen, Tapani; Jokikokko, Erkki; Kallio‐Nyberg, Irma; Harjunpää, Hannu

doi:10.1111/jai.13517

Cited by 8 publications

(8 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Injuries resulting from entanglement and incurred during removal are of particular concern, and have been associated with reduced longevity and hampered reproductive development (Baker & Schindler, ). The severity and nature of injuries are dependent both on how the individual is entangled in the net (e.g., loosely netted by the teeth, gills entangled and/or compressed, enmeshed around muscular tissue or bagged in net) and how it is removed from the net (e.g., pushed through or disentangled; Veneranta, Pakarinen, Jokikokko, Kallio‐Nyberg, & Harjunpää, ). In particular, injuries to the gills, potentially leading to exsanguination, and constrictions and bruising around the body due to net encirclement have been linked to fatal outcomes for fish (Kojima et al., ; Ng, Fredericks, & Quist, ).…”

Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

See 1 more Smart Citation

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

et al. 2018

View full text Add to dashboard Cite

Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.

show abstract

Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

“…Severe exhaustion can also result from the need to maintain position in the hanging net (Farrell, Gallaugher, Fraser, et al, 2001;Veneranta et al, 2018). Fish can be experience hypoxia not only during removal from the net, but also during capture if opercula are covered by netting, thereby suffocating fish.…”

Section: Ta B L E 1 (Continued)mentioning

confidence: 99%

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Whitefish fishing is mainly mixed-stock and mixed-form fishing in coastal waters. In addition, other fish species form a by-catch in whitefish fishing (Kallio-Nyberg et al, 2018;Veneranta, Pakarinen, Jokikokko, Kallio-Nyberg, & Harjunpää, 2017). Spatial knowledge of the status of the whitefish forms and stocks is currently limited, and more research is needed to identify the critical areas.…”

Section: Discussionmentioning

confidence: 99%

Different growth trends of whitefish ( Coregonus lavaretus ) forms in the northern Baltic Sea

et al. 2019

Self Cite

View full text Add to dashboard Cite

The sea growth of two whitefish forms, anadromous (Coregonus lavaretus lavaretus) and sea‐spawning (Coregonus lavaretus widegreni), was analysed using samples collected from the commercial sea catch in the Gulf of Bothnia (GoB) in the northern Baltic Sea during 1998–2014. In the GoB area, these two forms are possible to identify because the gill‐raker number and size at maturity vary between forms. The growth rate of the forms is linked to their feeding area. Sea‐spawning whitefish, which has a feeding migration near its home site, was shorter in the northern GoB (66°N–64°N) at the ages of 3–11 than those in the southern GoB (64°N–60°30′N). In the data, most whitefish were caught with gill nets in the GoB. The mesh sizes of gill nets capturing the anadromous form were mostly 35–45 mm, while those capturing the sea‐spawning form were <35 mm in the northern GoB. It is likely that the different growth trends for small and large whitefish were connected with differences in their recruitment for fishing. The length of anadromous females at the age of four sea years increased significantly, but the length of six‐year‐old anadromous female whitefish decreased over the catch years from 1998–2014. In contrast, the length of slow‐growing sea‐spawning whitefish of six years or older increased significantly in relation to the catch year in the gill‐net catch. The increase in the growth of young age groups in both forms was probably associated with the increasing temperature and the low fishing pressure on small fish. The decreasing age at capture for both forms and the depression of the mean size of old anadromous whitefish are signs of high fishing pressure with a high gill‐net effort that selectively removes the largest and oldest individuals of both forms.

show abstract

“…In sea trout fisheries, however, all mesh sizes up to 70 mm mainly catch undersized individuals. The gill‐net catch of the other fish species (Lehtonen & Jokikokko, ; Lehtonen et al, ) is low in comparison to the catch of whitefish in the Bothnian Sea and Bothnian Bay, especially in cold water periods (Veneranta, Pakarinen, Jokikokko, Kallio‐Nyberg, & Harjunpää, ). The increased use of smaller mesh sizes in the BS for migratory whitefish is a significant trend.…”

Section: Discussionmentioning

confidence: 99%

Anadromous trout threatened by whitefish gill-net fisheries in the northern Baltic Sea

et al. 2018

Self Cite

View full text Add to dashboard Cite

We estimated the effect of the gill‐net fisheries targeted at whitefish (Coregonus sp.) on anadromous sea trout, Salmo trutta, in the Gulf of Bothnia, Baltic Sea using separate data for fish species. The analysis of sea trout captures was based on tagging and recapture data collected in 1998–2011, while whitefish data were derived from individual samples of commercial fisheries from the same period. The mesh sizes used in gill‐net fishing and the seasonal and temporal distributions of recaptured sea trout and sampled whitefish were compared in the northern and southern Gulf of Bothnia. The trout had typically spent 1–2 years at sea, and they were mainly immature with a median body length of 40–43 cm at the time of recapture in gill nets. Despite the increase in the minimum permitted landing size from 40 to 50 cm in 2008, the median length of recaptured trout remained unchanged during the study period. Most (59%) of the gillnetted trout were caught in the southern Gulf of Bothnia in gill nets with mesh sizes of 40–45 mm, which were also used in the whitefish fishery (72%). In the northern Gulf of Bothnia, nets with a smaller mesh size of 25–39 mm took 83% of the whitefish catch and 39% from recaptured trout. In both areas, the overlap in mesh sizes used to gill‐net catch whitefish and sea trout increased during the study period. There were clear seasonal and areal differences in the relative probability of sea trout being captured in gill nets, suggesting that carefully tailored spatial and temporal restrictions on gill‐net fisheries could provide a tool to protect young sea trout without causing intolerable difficulties for the fisheries targeting other species.

show abstract

Mortality of Baltic sea trout (Salmo trutta) after release from gillnets

Cited by 8 publications

References 37 publications

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

Different growth trends of whitefish ( Coregonus lavaretus ) forms in the northern Baltic Sea

Anadromous trout threatened by whitefish gill-net fisheries in the northern Baltic Sea

Contact Info

Product

Resources

About