Responses in fisheries catch data to a warming ocean along a latitudinal gradient in the western Pacific Ocean

Dimarchopoulou, Donna; Makino, Mitsutaku; Prayoga, Mochammad Rachadian; Zeller, Dirk; Vianna, Gabriel M. S.; Humphries, Austin T.

doi:10.1007/s10641-021-01162-z

Cited by 11 publications

(6 citation statements)

References 59 publications

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“…The unmasked MTC pattern shows that average temperature of the species composition of the catch was stable at ~27.4°C. A stable MTC trend suggests that warmer‐water species were not entering the Gulf, perhaps because further tropicalisation of catches is limited for many tropical and subtropical water bodies around the world (Cheung et al., 2013; Dimarchopoulou et al., 2022; Keskin & Pauly, 2018; Liang et al., 2018; Tsikliras & Stergiou, 2014).…”

Section: Resultsmentioning

confidence: 99%

Mean temperature of the catch index can be masked by changes in catch composition unrelated to ocean warming

Alajmi,

Ben‐Hasan,

Alrushaid

et al. 2023

Fisheries Management Eco

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Oceans are increasingly warming through climate change. Fish and invertebrate ectotherms respond to ocean warming through poleward and depth‐related migrations, a consequence of which is disruption of fisheries catch compositions. Mean temperature of the catch (MTC) is an index of change in catch composition, from colder to warmer water species. MTC is widely applied as an easily parameterised variable using readily available data (catch and species preferred temperature), but few studies underscore situations that might mask the “true” MTC trend. Here, we use fisheries catch in the Arabian‐Persian Gulf (“Gulf”) to highlight, for the first time, how abrupt changes in market demand can strongly influence catch composition and thereby mask a trend in MTC, and discuss the implications of the unmasked MTC trend to fisheries in the region. We found that a recent sharp decline in MTC from 27 to 26°C, despite a gradual increase in sea surface temperature, coincided with an escalated demand for the largehead hairtail (Trichiurus lepturus), a relatively cold‐water species in the Gulf, that caused catch to dramatically increase for export to overseas markets. Our findings suggest that the change in MTC reflected a fishery response to satisfy increased international market demand, rather than reflecting warming‐driven changes in catch composition. When excluding the effect of T. lepturus catch, the Gulf MTC trend was stable over time and consistent with a trend in many tropical and subtropical waters. Our findings highlight that an MTC change can be masked by factors unrelated to warming‐driven changes in catch composition, and that catch‐only MTC trends should be examined cautiously.

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Section: Resultsmentioning

confidence: 99%

Mean temperature of the catch index can be masked by changes in catch composition unrelated to ocean warming

Alajmi,

Ben‐Hasan,

Alrushaid

et al. 2023

Fisheries Management Eco

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“…At 5° latitude by 5° longitude resolution, monthly values were averaged across years from 1950–2019. These SSTA data are relative to temperatures during the period from 1951–1980 ( Kaplan et al, 1998 ), and SSTA was chosen as temperature anomalies are considered to present a more consistent indicator of climate-change related ocean warming across large areas relative to absolute Sea Surface Temperatures ( Tsikliras & Stergiou, 2014 ; Tsikliras et al, 2015 ; Dimarchopoulou et al, 2021b ). We then performed simple linear regression and segmented linear regression of SSTA on time (Years).…”

Section: Methodsmentioning

confidence: 99%

“…One method to infer changes in the geographic distribution of marine fish and invertebrate populations includes the Mean Temperature of the Catch index (MTC, Cheung, Watson & Pauly, 2013 ). This index represents the catch-weighted mean temperature preference of species in the fisheries catch in an area, and has been applied to a variety of marine ecosystems globally (see Leitão et al, 2018 and Dimarchopoulou et al, 2021b and references therein). Overall, an increase in MTC over time indicates an ocean-warming induced increase in the proportion of species of warmer thermal affinity relatively to those of colder thermal affinity recorded in the catch ( Cheung, Watson & Pauly, 2013 ; Tsikliras & Stergiou, 2014 ; Liang, Xian & Pauly, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Fishery catch is affected by geographic expansion, fishing down food webs and climate change in Aotearoa, New Zealand

Lavin,

Pauly,

Dimarchopoulou

et al. 2023

PeerJ

Self Cite

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Historical fishing effort has resulted, in many parts of the ocean, in increasing catches of smaller, lower trophic level species once larger higher trophic level species have been depleted. Concurrently, changes in the geographic distribution of marine species have been observed as species track their thermal affinity in line with ocean warming. However, geographic shifts in fisheries, including to deeper waters, may conceal the phenomenon of fishing down the food web and effects of climate warming on fish stocks. Fisheries-catch weighted metrics such as the Mean Trophic Level (MTL) and Mean Temperature of the Catch (MTC) are used to investigate these phenomena, although apparent trends of these metrics can be masked by the aforementioned geographic expansion and deepening of fisheries catch across large areas and time periods. We investigated instances of both fishing down trophic levels and climate-driven changes in the geographic distribution of fished species in New Zealand waters from 1950–2019, using the MTL and MTC. Thereafter, we corrected for the masking effect of the geographic expansion of fisheries within these indices by using the Fishing-in-Balance (FiB) index and the adapted Mean Trophic Level (aMTL) index. Our results document the offshore expansion of fisheries across the New Zealand Exclusive Economic Zone (EEZ) from 1950–2019, as well as the pervasiveness of fishing down within nearshore fishing stock assemblages. We also revealed the warming of the MTC for pelagic-associated fisheries, trends that were otherwise masked by the depth- and geographic expansion of New Zealand fisheries across the study period.

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“…The Thermaikos Gulf is considered a mesotrophic system; however, extreme eutrophication events often occur under persistent southerly winds [15]. However, overall ecosystem degradation can be observed, with decreasing fish catches and biomass as a result of overfishing and environmental factors [18].…”

Section: Sampling Sitementioning

confidence: 99%

Temporal and Environmental Dynamics of Fish Stocks in the Marine Protected Area of the Artificial Reef of Kitros, Pieria (Northern Greece, Mediterranean Sea)

Kallianiotis,

Batjakas

2023

JMSE

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The impact of temporal factors and physiochemical properties on the quantities and biomass of fish in the Thermaikos Gulf and adjacent habitats around the Pieria artificial reef complex in Northern Greece was evaluated. Data were collected from edge habitats of an artificial reef made of submerged concrete blocks located offshore of Kitros. Between 2015 and 2017, sampling excursions took place in the spring, summer, and fall of each year. The artificial reef complex is positioned 11.5 km offshore from Kitros, near the delta of the Aliakmonas River, and is influenced by freshwater from the Axios, Aliakmonas, Ludias, and Gallikos Rivers. To estimate the biomass and numbers of the primary benthopelagic commercial fish in the region, nine experimental samples were taken from 2015 to 2017, employing a bottom trawl with a mesh size of 10 mm. Each trawl sample lasted for 30 min to reduce the environmental impact of fishing in the areas under study. The sampling schedule was aligned with factors like the breeding times of the dominant species and the seasonal changes in the thermocline zone. Analysis showed seasonal differences in average abundance and biomass values across the 3 years of the study. Mullus barbatus, recognized as the most commercially significant species caught, demonstrated the greatest abundance and biomass during the second sampling season. Conversely, Pagellus erythrinus, the second most vital commercial species caught, exhibited its highest abundance in the first season and reached its peak biomass during the third sampling season. Hierarchical cluster analyses showed that the two major resulting clusters of species proliferated in numbers over the 3-year period, while undergoing a concurrent reduction in their individual sizes.

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Responses in fisheries catch data to a warming ocean along a latitudinal gradient in the western Pacific Ocean

Cited by 11 publications

References 59 publications

Mean temperature of the catch index can be masked by changes in catch composition unrelated to ocean warming

Mean temperature of the catch index can be masked by changes in catch composition unrelated to ocean warming

Fishery catch is affected by geographic expansion, fishing down food webs and climate change in Aotearoa, New Zealand

Temporal and Environmental Dynamics of Fish Stocks in the Marine Protected Area of the Artificial Reef of Kitros, Pieria (Northern Greece, Mediterranean Sea)

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