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Sørdalen TK, Halvorsen KT, Olsen EM. Protection from fishing improves body growth of an exploited species. Proc Biol Sci 2022; 289:20221718. [DOI: 10.1098/rspb.2022.1718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Hunting and fishing are often size-selective, which favours slow body growth. In addition, fast growth rate has been shown to be positively correlated with behavioural traits that increase encounter rates and catchability in passive fishing gears such as baited traps. This harvest-induced selection should be effectively eliminated in no-take marine-protected areas (MPAs) unless strong density dependence results in reduced growth rates. We compared body growth of European lobster (
Homarus gammarus
) between three MPAs and three fished areas. After 14 years of protection from intensive, size-selective lobster fisheries, the densities in MPAs have increased considerably, and we demonstrate that females moult more frequently and grow more during each moult in the MPAs. A similar, but weaker pattern was evident for males. This study suggests that MPAs can shield a wild population from slow-growth selection, which can explain the rapid recovery of size structure following implementation. If slow-growth selection is a widespread phenomenon in fisheries, the effectiveness of MPAs as a management tool can be higher than currently anticipated.
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Affiliation(s)
- Tonje Knutsen Sørdalen
- Centre for Coastal Research, Department of Natural Sciences, University of Agder, N-4604 Kristiansand, Norway
- Institute of Marine Research, Flødevigen, Nye Flødevigvei 20, N-4817 His, Norway
| | | | - Esben Moland Olsen
- Centre for Coastal Research, Department of Natural Sciences, University of Agder, N-4604 Kristiansand, Norway
- Institute of Marine Research, Flødevigen, Nye Flødevigvei 20, N-4817 His, Norway
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2
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Villegas‐Ríos D, Freitas C, Moland E, Olsen EM. Eco‐evolutionary dynamics of Atlantic cod spatial behavior maintained after the implementation of a marine reserve. Evol Appl 2022; 15:1846-1858. [PMID: 36426127 PMCID: PMC9679232 DOI: 10.1111/eva.13483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 12/05/2022] Open
Abstract
The effects of marine reserves on the life history and demography of the protected populations are well‐established, typically increasing population density and body size. However, little is known about how marine reserves may alter the behavior of the populations that are the target of protection. In theory, marine reserves can relax selection on spatial behavioral phenotypes that were previously targeted by the fishery and also drive selection in favor of less mobile individuals. In this study, we used acoustic telemetry to monitor the individual spatial behavior of 566 Atlantic cod (Gadus morhua Linnaeus, 1758) moving within a marine reserve and a control site in southern Norway, starting 1 year before the implementation of the marine reserve and lasting up to 9 years after. Following a before‐after‐control‐impact approach, we investigated changes in (1) survival, (2) selection acting on behavioral traits, and (3) mean behavioral phenotypes, after the implementation of the marine reserve. We focused on three behavioral traits commonly used to describe the mobility of aquatic animals: home range size, depth position, and diel vertical migration range. Survival increased after reserve implementation, but contrary to our expectations, it subsequently decreased to preprotection levels after just 3 years. Further, we found no significance in selection patterns acting on any of the three behavioral traits after reserve implementation. Although some changes related to water column use (the tendency to occupy deeper waters) were observed in the marine reserve after 9 years, they cannot unequivocally be attributed to protection. Our results show that survival and behavioral responses to marine reserves in some cases may be more complex than previously anticipated and highlight the need for appropriately scaled management experiments and more integrated approaches to understand the effects of marine protected areas on harvested aquatic species.
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Affiliation(s)
- David Villegas‐Ríos
- Instituto Mediterráneo de Estudios Avanzados (CSIC‐UiB) Esporles Spain
- Instituto de Investigaciones Marinas (IIM‐CSIC) Vigo Spain
| | - Carla Freitas
- Institute of Marine Research His Norway
- MARE, Marine and Environmental Sciences Center Madeira Tecnopolo Funchal Portugal
| | - Even Moland
- Institute of Marine Research His Norway
- Department of Natural Sciences, Centre for Coastal Research (CCR) University of Agder Kristiansand Norway
| | - Esben M. Olsen
- Institute of Marine Research His Norway
- Department of Natural Sciences, Centre for Coastal Research (CCR) University of Agder Kristiansand Norway
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3
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Halvorsen KT, Larsen T, Browman HI, Durif C, Aasen N, Vøllestad LA, Cresci A, Sørdalen TK, Bjelland RM, Skiftesvik AB. Movement patterns of temperate wrasses (Labridae) within a small marine protected area. JOURNAL OF FISH BIOLOGY 2021; 99:1513-1518. [PMID: 34159592 DOI: 10.1111/jfb.14825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/22/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
The movement patterns of three commercially important wrasse (Labridae) species inside a small marine protected area (~ 0.15 km2 ) on the west coast of Norway were analysed over a period of 21 months. The mean distance between capture and recapture locations varied between 10 and 187 m, and was species and season specific. The extent of movement was not related to body size or sex. These results imply that a network of small strategically located marine protected areas can be used as management tools to protect wrasses from size- and sex-selective fishing mortality.
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Affiliation(s)
- Kim Tallaksen Halvorsen
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Torkel Larsen
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Howard I Browman
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Caroline Durif
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Nicolai Aasen
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
| | - Leif Asbjørn Vøllestad
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
| | - Alessandro Cresci
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | | | - Reidun M Bjelland
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Anne Berit Skiftesvik
- Ecosystem Acoustics Group, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
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4
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Norderhaug KM, Nedreaas K, Huserbråten M, Moland E. Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic. AMBIO 2021; 50:163-173. [PMID: 32720251 PMCID: PMC7708581 DOI: 10.1007/s13280-020-01362-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 04/23/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
In this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.
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Affiliation(s)
- Kjell Magnus Norderhaug
- Institute of Marine Research IMR, Norway, Nye Flødevigveien 20, 4817 His, Norway
- University of Oslo Norway, Oslo, Norway
| | - Kjell Nedreaas
- Institute of Marine Research, Norway, Nordnesgaten 33, 5005 Bergen, Norway
| | - Mats Huserbråten
- Institute of Marine Research, Norway, Nordnesgaten 50, 5005 Bergen, Norway
| | - Even Moland
- Institute of Marine Research, Norway, Nye Flødevigveien 20, 4817 His, Norway
- Centre for Coastal Research (CCR), University of Agder, Kristiansand, Norway
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5
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Fernández-Chacón A, Villegas-Ríos D, Moland E, Baskett ML, Olsen EM, Carlson SM. Protected areas buffer against harvest selection and rebuild phenotypic complexity. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02108. [PMID: 32096584 DOI: 10.1002/eap.2108] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 01/23/2020] [Accepted: 01/30/2020] [Indexed: 06/10/2023]
Abstract
Harvest mortality typically truncates the harvested species' size structure, thereby reducing phenotypic complexity, which can lead to reduced population productivity, increased population variability, and selection on an array of life history traits that can further alter these demographic processes. Marine protected areas (MPAs) are a potential tool to protect older, larger individuals and therefore mitigate such ecological and evolutionary effects of harvest, depending on the degree of connectivity among areas. Such MPA protection relies on a shift in size-dependent mortality, the measurement of which can therefore serve as an early indicator of whether MPAs might achieve the desired longer-term ecological and evolutionary responses. We directly measured MPA effects on size-selective mortality and associated size structure using mark-recapture data on European lobster (Homarus gammarus) collected at three MPA-control area pairs in southern Norway during one decade (n = 5,943). Mark-recapture modeling, accounting for variation in recapture probabilities, revealed (1) that annual mean survival was higher inside MPAs (0.592) vs. control areas (0.298) and (2) that significant negative relationships between survival and body size occurred at the control areas but not in the MPAs, where the effect of body size was predominantly positive. Additionally, we found (3) that mean and maximum body size increased over time inside MPAs but not in control areas. Overall, our results suggest that MPAs can rebuild phenotypic complexity (i.e., size structure) and provide protection from harvest selection.
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Affiliation(s)
- Albert Fernández-Chacón
- Joint Research Unit for Biodiversity (UO, CSIC, PA), University of Oviedo, 33600, Mieres, Spain
- Department of Natural Sciences, Centre for Coastal Research, University of Agder, P.O. Box 422, 4604, Kristiansand, Norway
| | - David Villegas-Ríos
- Department of Ecology and Marine Resources, Ichthyology Group, IMEDEA, Instituto Mediterráneo de Estudios Avanzados (CSIC-UIB), C/Miquel Marquès 21, 07190, Esporles, Balearic Islands, Spain
- Department of Ecology and Marine Resources, Fisheries Ecology Group, Instituto de Investigaciones Marinas (IIM-CSIC), Eduardo Cabello 6, 36208, Vigo, Pontevedra, Spain
| | - Even Moland
- Department of Natural Sciences, Centre for Coastal Research, University of Agder, P.O. Box 422, 4604, Kristiansand, Norway
- Institute of Marine Research, Nye Flødevigveien 20, 4817, His, Norway
| | - Marissa L Baskett
- Department of Environmental Science and Policy, University of California, Davis, One Shields Avenue, Davis, California, 95616, USA
| | - Esben M Olsen
- Department of Natural Sciences, Centre for Coastal Research, University of Agder, P.O. Box 422, 4604, Kristiansand, Norway
- Institute of Marine Research, Nye Flødevigveien 20, 4817, His, Norway
| | - Stephanie M Carlson
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA
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6
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Nater CR, Vindenes Y, Aass P, Cole D, Langangen Ø, Moe SJ, Rustadbakken A, Turek D, Vøllestad LA, Ergon T. Size- and stage-dependence in cause-specific mortality of migratory brown trout. J Anim Ecol 2020; 89:2122-2133. [PMID: 32472576 DOI: 10.1111/1365-2656.13269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/06/2020] [Indexed: 12/21/2022]
Abstract
Evidence-based management of natural populations under strong human influence frequently requires not only estimates of survival but also knowledge about how much mortality is due to anthropogenic vs. natural causes. This is the case particularly when individuals vary in their vulnerability to different causes of mortality due to traits, life history stages, or locations. Here, we estimated harvest and background (other cause) mortality of landlocked migratory salmonids over half a century. In doing so, we quantified among-individual variation in vulnerability to cause-specific mortality resulting from differences in body size and spawning location relative to a hydropower dam. We constructed a multistate mark-recapture model to estimate harvest and background mortality hazard rates as functions of a discrete state (spawning location) and an individual time-varying covariate (body size). We further accounted for among-year variation in mortality and migratory behaviour and fit the model to a unique 50-year time series of mark-recapture-recovery data on brown trout (Salmo trutta) in Norway. Harvest mortality was highest for intermediate-sized trout, and outweighed background mortality for most of the observed size range. Background mortality decreased with body size for trout spawning above the dam and increased for those spawning below. All vital rates varied substantially over time, but a trend was evident only in estimates of fishers' reporting rate, which decreased from over 50% to less than 10% throughout the study period. We highlight the importance of body size for cause-specific mortality and demonstrate how this can be estimated using a novel hazard rate parameterization for mark-recapture models. Our approach allows estimating effects of individual traits and environment on cause-specific mortality without confounding, and provides an intuitive way to estimate temporal patterns within and correlation among different mortality sources.
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Affiliation(s)
- Chloé R Nater
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Yngvild Vindenes
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Per Aass
- Zoological Museum, The Natural History Museums and Botanical Garden, University of Oslo, Oslo, Norway
| | - Diana Cole
- School of Mathematics, Statistics and Actuarial Science, University of Kent, Canterbury, UK
| | - Øystein Langangen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - S Jannicke Moe
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
| | | | - Daniel Turek
- Department of Mathematics and Statistics, Williams College, Williamstown, MA, USA
| | - Leif Asbjørn Vøllestad
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Torbjørn Ergon
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
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7
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Ono K, Knutsen H, Olsen EM, Ruus A, Hjermann DØ, Chr Stenseth N. Possible adverse impact of contaminants on Atlantic cod population dynamics in coastal ecosystems. Proc Biol Sci 2019; 286:20191167. [PMID: 31362638 DOI: 10.1098/rspb.2019.1167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
While many in-laboratory ecotoxicological studies have shown the adverse impact of pollutants to the fitness of an individual, direct evidence from the field on the population dynamics of wildlife animals has been lacking. Here, we provide empirical support for a negative effect of pollution on Atlantic cod (Gadus morhua) population dynamics in coastal waters of Norway by combining unique time series of juvenile cod abundance, body size, environmental concentration of toxic contaminants and a spatially structured population dynamics model. The study shows that mercury concentration might have decreased the reproductive potential of cod in the region despite the general decline in the environmental concentration of mercury, cadmium and hexachlorobenzene since the implementation of national environmental laws. However, some cod populations appeared to be more resistant to mercury pollution than others, and the strength and shape of mercury effect on cod reproductive potential was fjord-specific. Additionally, cod growth rate changed at scales smaller than fjords with a gradient related to the exposure to the open ocean and offshore cod. These spatial differences in life-history traits emphasize the importance of local adaptation in shaping the dynamics of local wildlife populations. Finally, this study highlights the possibility to mitigate pollution effects on natural populations by reducing the overall pollution level, but also reveals that pollution reduction alone is not enough to rebuild local cod populations. Cod population recovery probably requires complementary efforts on fishing regulation and habitat restoration.
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Affiliation(s)
- Kotaro Ono
- Centre for Coastal Research (CCR), University of Agder, 4604 Kristiansand, Norway.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
| | - Halvor Knutsen
- Centre for Coastal Research (CCR), University of Agder, 4604 Kristiansand, Norway.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.,Institute of Marine Research, Flødevigen, 4817 His, Norway
| | - Esben M Olsen
- Centre for Coastal Research (CCR), University of Agder, 4604 Kristiansand, Norway.,Institute of Marine Research, Flødevigen, 4817 His, Norway
| | - Anders Ruus
- Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.,Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway
| | - Dag Ø Hjermann
- Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway
| | - Nils Chr Stenseth
- Centre for Coastal Research (CCR), University of Agder, 4604 Kristiansand, Norway.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
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8
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Roney NE, Oomen RA, Knutsen H, Olsen EM, Hutchings JA. Fine-scale population differences in Atlantic cod reproductive success: A potential mechanism for ecological speciation in a marine fish. Ecol Evol 2018; 8:11634-11644. [PMID: 30598762 PMCID: PMC6303701 DOI: 10.1002/ece3.4615] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/23/2018] [Accepted: 09/05/2018] [Indexed: 11/30/2022] Open
Abstract
Successful resource-management and conservation outcomes ideally depend on matching the spatial scales of population demography, local adaptation, and threat mitigation. For marine fish with high dispersal capabilities, this remains a fundamental challenge. Based on daily parentage assignments of more than 4,000 offspring, we document fine-scaled temporal differences in individual reproductive success for two spatially adjacent (<10 km) populations of a broadcast-spawning marine fish. Distinguished by differences in genetics and life history, Atlantic cod (Gadus morhua) from inner- and outer-fjord populations were allowed to compete for mating and reproductive opportunities. After accounting for phenotypic variability in several traits, reproductive success of outer-fjord cod was significantly lower than that of inner-fjord cod. This finding, given that genomically different cod ecotypes inhabit inner- and outer-fjord waters, raises the intriguing hypothesis that the populations might be diverging because of ecological speciation. Individual reproductive success, skewed within both sexes (more so among males), was positively affected by body size, which also influenced the timing of reproduction, larger individuals spawning later among females but earlier among males. Our work suggests that spatial mismatches between management and biological units exist in marine fishes and that studies of reproductive interactions between putative populations or ecotypes can provide an informative basis on which determination of the scale of local adaptation can be ascertained.
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Affiliation(s)
- Nancy E. Roney
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Rebekah A. Oomen
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of BiosciencesUniversity of OsloOsloNorway
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
| | - Halvor Knutsen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of BiosciencesUniversity of OsloOsloNorway
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
- Centre for Coastal Research (CCR)University of AgderKristiansandNorway
| | - Esben M. Olsen
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
- Centre for Coastal Research (CCR)University of AgderKristiansandNorway
| | - Jeffrey A. Hutchings
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of BiosciencesUniversity of OsloOsloNorway
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
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9
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Knutsen H, Jorde PE, Hutchings JA, Hemmer‐Hansen J, Grønkjær P, Jørgensen KM, André C, Sodeland M, Albretsen J, Olsen EM. Stable coexistence of genetically divergent Atlantic cod ecotypes at multiple spatial scales. Evol Appl 2018; 11:1527-1539. [PMID: 30344625 PMCID: PMC6183466 DOI: 10.1111/eva.12640] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/09/2018] [Indexed: 12/15/2022] Open
Abstract
Coexistence in the same habitat of closely related yet genetically different populations is a phenomenon that challenges our understanding of local population structure and adaptation. Identifying the underlying mechanisms for such coexistence can yield new insight into adaptive evolution, diversification and the potential for organisms to adapt and persist in response to a changing environment. Recent studies have documented cryptic, sympatric populations of Atlantic cod (Gadus morhua) in coastal areas. We analysed genetic origin of 6,483 individual cod sampled annually over 14 years from 125 locations along the Norwegian Skagerrak coast and document stable coexistence of two genetically divergent Atlantic cod ecotypes throughout the study area and study period. A "fjord" ecotype dominated in numbers deep inside fjords while a "North Sea" ecotype was the only type found in offshore North Sea. Both ecotypes coexisted in similar proportions throughout coastal habitats at all spatial scales. The size-at-age of the North Sea ecotype on average exceeded that of the fjord ecotype by 20% in length and 80% in weight across all habitats. Different growth and size among individuals of the two types might be one of several ecologically significant variables that allow for stable coexistence of closely related populations within the same habitat. Management plans, biodiversity initiatives and other mitigation strategies that do not account for the mixture of species ecotypes are unlikely to meet objectives related to the sustainability of fish and fisheries.
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Affiliation(s)
- Halvor Knutsen
- Institute of Marine ResearchFlødevigenHisNorway
- Department of BiosciencesCentre for Ecological and Evolutionary Synthesis (CEES)University of OsloBlindernOsloNorway
- Centre for Coastal ResearchUniversity of AgderKristiansandNorway
| | - Per Erik Jorde
- Institute of Marine ResearchFlødevigenHisNorway
- Department of BiosciencesCentre for Ecological and Evolutionary Synthesis (CEES)University of OsloBlindernOsloNorway
| | - Jeffrey A. Hutchings
- Institute of Marine ResearchFlødevigenHisNorway
- Department of BiosciencesCentre for Ecological and Evolutionary Synthesis (CEES)University of OsloBlindernOsloNorway
- Department of BiologyDalhousie UniversityHalifaxNSCanada
| | - Jakob Hemmer‐Hansen
- Section for Marine Living ResourcesNational Institute of Aquatic ResourcesTechnical University of DenmarkSilkeborgDenmark
| | - Peter Grønkjær
- Department for BioscienceAarhus UniversityAquatic BiologyAarhusDenmark
| | | | - Carl André
- Department of Marine Sciences – TjärnöUniversity of GothenburgStrömstadSweden
| | - Marte Sodeland
- Centre for Coastal ResearchUniversity of AgderKristiansandNorway
| | | | - Esben M. Olsen
- Institute of Marine ResearchFlødevigenHisNorway
- Centre for Coastal ResearchUniversity of AgderKristiansandNorway
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10
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Elliott SAM, Ahti PA, Heath MR, Turrell WR, Bailey DM. An assessment of juvenile Atlantic cod Gadus morhua distribution and growth using diver operated stereo-video surveys. JOURNAL OF FISH BIOLOGY 2016; 89:1190-1207. [PMID: 27221152 PMCID: PMC4999031 DOI: 10.1111/jfb.12998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/07/2016] [Indexed: 06/05/2023]
Abstract
Stereo-video scuba transects were conducted during daylight hours from June to September 2013 within a proposed marine protected area (MPA) in the Firth of Clyde, west of Scotland. More juvenile Atlantic cod Gadus morhua of fork length (LF ) range 6-11 cm were observed in substrata containing mixed gravel, including maerl, than in boulder-cobble substrata with high algal cover, or sand with low density seagrass. Community composition was significantly different between substratum types. A decrease in G. morhua abundance was observed over the period of data collection. Over time, mean and variance in G. morhua LF increased, indicating multiple recruitment events. Protecting mixed gravel substrata could be a beneficial management measure to support the survival and recruitment of juvenile G. morhua; other substrata might be important at night given their diel migratory behaviour. Stereo-video cameras provide a useful non-destructive fisheries-independent method to monitor species abundance and length measurements.
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Affiliation(s)
- S A M Elliott
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, U.K
| | - P A Ahti
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, U.K
| | - M R Heath
- Department of Mathematics and Statistics, University of Strathclyde, 16 Richmond Street, Glasgow, G1 1XQ, U.K
| | - W R Turrell
- Marine Scotland Science, Marine Laboratory, P. O. Box 101, 375 Victoria Road, Aberdeen, AB11 9DB, U.K
| | - D M Bailey
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, U.K
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