Migration

Righton, David; Metcalfe, Julian D.

doi:10.1002/9781119460701.ch5

Cited by 3 publications

(3 citation statements)

References 199 publications

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“…We found that SSB recovery is limited by the inter action of F and external abiotic and biotic dynamics such as increasing temperature and decreasing abundance of large copepods. Increasing temperatures play an important role for the life history traits of cod, causing faster growth rates and a decrease in age of maturity (Drinkwater 2005, Righton & Metcalfe 2019. In addition, fecundity and cod condition in crease with increasing bottom temperature (Rose 2019).…”

Section: Discussionmentioning

confidence: 99%

Discontinuous dynamics in North Sea cod Gadus morhua caused by ecosystem change

Blöcker,

Sguotti,

Möllmann

2023

Mar. Ecol. Prog. Ser.

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Marine ecosystems worldwide experience abrupt changes and regime shifts in structure and functioning due to the interacting effects of multiple stressors. North Sea cod Gadus morhua is a key example of a species being strongly overexploited for decades, causing an abrupt stock decrease below scientifically advised sustainable levels. Despite reductions in fishing pressure in recent years, populations of North Sea cod have not yet recovered. Why recovery is hindered and especially how ecosystem dynamics interacted with fishing to create a stable low cod stock is an open question. Here, we sequentially apply change point and principle component analyses as well as stochastic cusp modelling to a long-term time series (1963-2018) to show that North Sea cod recovery is limited due to an interaction of fishing pressure, internal stock dynamics and external environmental changes. We found that cod biomass experienced nonlinear, discontinuous dynamics, given the interaction of fishing pressure and climate change-induced increases in temperatures, wind magnitude and the North Atlantic Oscillation. Our results further demonstrate discontinuity in cod biomass due to low recruitment caused by a discontinuous relationship between stock biomass and environmental changes characterized by climate and zooplankton variables. Our study indicates that climate-induced changes in the environment have trapped North Sea cod in a depleted state, limiting the probability that the population will regain its role as a main target species for fisheries. Hence, we highlight the importance of incorporating discontinuous dynamics in fisheries management approaches to achieve sustainable exploitation levels and to identify thresholds of drivers to favour policies to prevent regime shifts.

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Section: Discussionmentioning

confidence: 99%

Discontinuous dynamics in North Sea cod Gadus morhua caused by ecosystem change

Blöcker,

Sguotti,

Möllmann

2023

Mar. Ecol. Prog. Ser.

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“…One of the most widely applied methods to study the movements of wild animals is to use individual markers. Particularly, conventional tagging experiments, which provide information on release and recapture positions, and are used for investigating broad-scale patterns such as area of utilisation and movement patterns of individuals (e.g., Righton & Metcalfe 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Cod migratory behaviour has been shown to vary markedly with respect to area, season, and major environmental factors (Pálsson & Thorsteinsson 2003). Cod of the same population may adopt different migration routes between areas and their speed of travel can vary considerably during and between journeys (Righton & Metcalfe 2019). Differences in migratory strategies have also been identified, with some cod remaining relatively stationary, while others redistribute over vast spatial distances that exceed 1000 km (Robichaud & Rose 2004).…”

Section: Introductionmentioning

confidence: 99%

New perspectives on Eastern Baltic cod movement patterns from historical and contemporary tagging data

Mion

Griffiths

Bartolino

et al. 2022

Mar. Ecol. Prog. Ser.

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Knowledge of the movement patterns and area utilisation of commercially important fish stocks is critical to management. The Eastern Baltic cod Gadus morhua, one of the most commercially and ecologically important stocks in the Baltic Sea, is currently one of the most severely impacted fish stocks in Europe. During the last 2 decades, this stock has experienced drastic decreases in population size, distributional range, individual growth and body condition, all of which may have affected the movements between different areas of the Baltic Sea. In this study, we investigated the seasonal movement patterns of Eastern Baltic cod by re-analysing historical tagging data collected by the countries surrounding the Baltic Sea (1955-1988) and compared historical patterns with contemporary data from a recent international tagging experiment (2016-2019). Our re-analyses of historical data showed the presence of different movement behaviours, i.e. resident or seasonally migratory, with larger distances moved by cod released in the northern and central Baltic areas compared to cod released in the southern Baltic areas. Furthermore, trends from the recent tagging experiment indicate a persistent resident strategy in the southern Baltic area. These findings present additional information on general movement patterns and area utilisation of Eastern Baltic cod that could inform future management actions and aid stock recovery.

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Northern cod re-establish historical migration patterns linked to capelin: insights from pop-up satellite archival tags

Rose,

Rowe

2024

Can. J. Fish. Aquat. Sci.

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In May of 2012 to 2015, 90 large (85-117 cm) Northern cod (Gadus morhua) with pop-up satellite archival tags (PSATs) set to release one year later were released from offshore spawning aggregations on the northeast Newfoundland shelf. Forty-nine (54%) transmitted or were recovered; 82% migrated inshore, 15% remained offshore (balance predated). Geo-locations were based on release, capture, and surfacing positions, and at tag-recorded depths < 50 m, on Kalman predicted light-based longitudes matched with coastal bathymetry. Migrating fish moved southwestward on average 5o longitude (350 km) and 2o latitude (222 km) to the northeast coast of Newfoundland, southern Labrador and northern Grand Bank, as historically from similar release points. Migration onset through the Labrador Current (< 0 oC) and arrival inshore were correlated with capelin (Mallotus villosus) peak spawning, inshore duration with capelin and cod biomass. Both species were delayed a month from historical norms. The probability of a cod remaining inshore after Dec 1st was 50%, which could impact time-dependent surveys. Fishing exploitation was 6%, predation 5%. Northern cod have re-established historical spatial migration patterns, with capelin a key influence on timing and duration inshore.

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Migration

Cited by 3 publications

References 199 publications

Discontinuous dynamics in North Sea cod Gadus morhua caused by ecosystem change

Discontinuous dynamics in North Sea cod Gadus morhua caused by ecosystem change

New perspectives on Eastern Baltic cod movement patterns from historical and contemporary tagging data

Northern cod re-establish historical migration patterns linked to capelin: insights from pop-up satellite archival tags

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