Historical dynamics of the demersal fish community in the East and South China Seas

2020 ◽  
Vol 71 (9) ◽  
pp. 1073 ◽  
Author(s):  
Jin Gao ◽  
James T. Thorson ◽  
Cody Szuwalski ◽  
Hui-Yu Wang
Keyword(s):  
South China ◽  
Collaborative Work ◽  
Habitat Preferences ◽  
Fishing Effort ◽  
Otter Trawl ◽  
Historical Records ◽  
China Seas ◽  
Important Species ◽  
Catch Rates ◽  
Abundance And Distribution

Taiwan has a long history of fishery operations and contributes significantly to the global fishery harvest. The East and South China seas are important fishing grounds for which publicly available data are very limited. More efforts are needed to digitise and analyse historical catch rate data to illuminate species and community changes in this region. In this study we digitised historical records of catch and effort from government fishery reports for nine commercial species caught by otter trawl, and reported quarterly from 1970 to 2001, from the East and South China seas. We analysed the four seasons and present abundance indices, distributions and among-species correlations for nine commercially important species from 1970 to 1988 (a period with high fishing effort) using a multispecies spatiotemporal model that estimates both covariation in multispecies catch rates, attributed to spatial habitat preferences and environmental responses, and indices representing trends in abundance and distribution. We found substantial spatial, temporal and spatiotemporal variation in the distribution of fishes and season-specific patterns. We recommend collaborative work from various adjacent countries to digitise historical records of fishing catch rates, because more records would potentially address scientific disagreements regarding trends in the abundance and distribution of commercial fishes in this region through comparative studies.

scholarly journals Environmental and fisheries effects on Gracilechinus acutus (Echinodermata: Echinoidea) distribution: is it a suitable bioindicator of trawling disturbance?

2012 ◽  
Vol 69 (8) ◽  
pp. 1457-1465 ◽  
Author(s):  
J. M. González-Irusta ◽  
A. Punzón ◽  
A. Serrano
Keyword(s):  
Habitat Preferences ◽  
Fishing Effort ◽  
Otter Trawl ◽  
Sediment Type ◽  
Trawl Fishery ◽  
Sediment Types ◽  
Initial Hypothesis ◽  
Wet Weight ◽  
Using Data ◽  
The Impact

AbstractGonzález-Irusta, J. M., Punzón, A., and Serrano, A. 2012. Environmental and fisheries effects on Gracilechinus acutus (Echinodermata: Echinoidea) distribution: is it a suitable bioindicator of trawling disturbance? – ICES Journal of Marine Science, 69: . Habitat preferences of Gracilechinus acutus in the southern Bay of Biscay were studied using data from autumn bottom-trawl surveys. Wet weight and number of specimens of G. acutus were obtained and related to environmental variables (depth, sediment type, and organic matter percentage) at each haul and to trawl fishing effort. With this information and the otter trawl effort data, the environmental requirements and the impact of the trawl fishery on G. acutus populations were analysed. Although the species was present in all depth strata and all sediment types studied, it had clear habitat preferences, as greater abundances and mean weight values were found at depths ranging from 71 to 200 m and in bottom sediments dominated by coarse and medium sands. The effect of disturbance by trawling on this echinoid was significant and clearly negative. Seabeds exposed to higher trawling disturbance showed lower values of urchin abundance and smaller urchins than areas with lower disturbance. Results of the present study confirm the initial hypothesis of the suitability of using this urchin as a bioindicator of trawling impact but only in areas with appropriate environmental conditions, highlighting the importance of attaining a wider knowledge on the essential habitat of the species.

Preliminary observations on abundance and distribution of fish fauna in a canyon of the Bay of Biscay (ICES Division 8c)

2021 ◽  
pp. 1-10
Author(s):  
G. Diez ◽  
L. Arregi ◽  
M. Basterretxea ◽  
E. Cuende ◽  
I. Oyarzabal
Keyword(s):  
Deep Sea ◽  
Basque Country ◽  
Fish Fauna ◽  
Fishing Effort ◽  
Fishing Gear ◽  
Clear Trend ◽  
Depth Ranges ◽  
Abundance And Distribution ◽  
Sea Fish ◽  
Distribution Of Fish

Abstract The changes in abundance and biodiversity of deep-sea fish fauna are described based on an annual deep-water longline survey with data collected during the period 2015–2019 in the Basque Country continental Slope (ICES Division 8c). The sampling scheme included hauls in four 400 m strata, from 650–2250 m deep. The DST sensors installed in the main line have allowed us to set an accurate soak time for each haul, and they were used to calculate fishing effort and CPUE by haul. The catchability of the fishing gear indicated that 15% of the total hooks deployed in the five-year period were able to fish, and that the bottom longline was very effective in fishing a wide number of different species in all depth ranges. The fishing gear caught 14 different species of sharks (13 deepwater and one pelagic), two chimaeras and nine teleosts. The abundance and biomass registered on the hooks attached to the bottom were between three and four times higher than in the floating sections, and the highest CPUE and biomass were recorded between 1051–1450 m, from 2015 to 2017, and in the 1451–1850 m strata, but they do not show any clear trend throughout the five years of the series.

Postsmolt Atlantic Salmon (Salmo salar) in the Labrador Sea

1991 ◽  
Vol 48 (1) ◽  
pp. 2-6 ◽  
Author(s):  
D. G. Reddin ◽  
P. B. Short
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Age Distribution ◽  
Labrador Sea ◽  
Scale Reading ◽  
Gill Nets ◽  
Atlantic Salmon Salmo Salar ◽  
Catch Rates ◽  
Abundance And Distribution ◽  
High Catch

In order to learn more about the existence, abundance, and distribution of postsmolt Atlantic salmon (Salmo salar) in the Labrador Sea, exploratory fishing was done with surface-set gill nets in early autumn of 1987 and 1988. In total, there were 468 salmon of various sea ages captured, of which 207 were postsmolts. The high catch rates compared with catch rates from Greenland suggest that the population of postsmolts in the Labrador Sea may be large. Postsmolts from rivers in Maine to Labrador were caught in the Labrador Sea, as indicated by Carlin tags and river age distribution from scale reading. The highest catch rates of postsmolts occurred in the Labrador Sea between 56° and 58°N latitude.

Aspects of the fishery, maturation and net selectivity of the wedge sole (Dicologoglossa cuneata) off south-western Iberia: implications for fishery management

2009 ◽  
Vol 90 (7) ◽  
pp. 1465-1474 ◽  
Author(s):  
Miguel Neves Santos ◽  
Pedro Gil Lino
Keyword(s):  
Fishery Management ◽  
River Mouth ◽  
Mesh Size ◽  
Scientific Basis ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Gill Net ◽  
Catch Rates ◽  
Log Normal ◽  
First Maturity

The wedge sole (Dicologoglossa cuneata, Moreau 1881) is a commercially important species for the artisanal fleet operating off the south-western Iberian Peninsula. During 2004 and 2005 a study was undertaken aiming to provide a scientific basis for management. Data collection included information on aspects of the fishery, spawning season, size at first maturity, tangle and gill-net selectivity. Seven nominal mesh sizes were used (40, 45 and 50 mm tangle nets and 40, 50, 60 and 70 mm gill-nets). Spawning lasts from December to June, with peaks in March and May. Length at first maturity for females was estimated at 18.5 cm. Catch rates decreased sharply with increasing mesh size, with tangle nets providing the highest yields. The log-normal selectivity model provided the best fit for specimens that were wedged. The higher catch-per-unit-effort of the smaller mesh sizes and the modal length of the fitted selectivity curve being below the size-at-maturity for wedge sole, suggests that the 50 mm nominal mesh size tangle net is the most appropriate for ensuring the fishery sustainability. Nevertheless, the minimum legal size should increase to at least 18 cm and a time–area closure should be implemented off the Guadiana River mouth.

China

2021 ◽  
pp. 170-205
Author(s):  
Stephen E. Gent ◽  
Mark J. C. Crescenzi
Keyword(s):  
Rare Earth ◽  
Dispute Resolution ◽  
Market Power ◽  
South China ◽  
Deep Sea ◽  
International Institutions ◽  
Gray Zone ◽  
China Seas ◽  
Mineral Extraction ◽  
International Seabed Authority

This chapter examines how the pursuit of market power over rare earth elements (REEs) influences China’s use of strategic delay in East and South China Seas. As the dominant global producer of REEs, China has the ability to set prices in this market. The desire to maintain this market power motivates China to continue to push its long-standing claims to sovereignty over seabed resources in the East and South China Seas. International institutions such as UNCLOS and the International Seabed Authority do not provide a dispute-resolution option that allows China to maintain unfettered access to deep sea mineral extraction. At the same time, China’s economic dependence on Japan and the global REE market constrains China from turning to military escalation to press its claims. Instead, China has relied upon strategic delay and gray zone tactics to gradually expand its presence in the East and South China Seas.

The demersal fishery in the Clyde Sea Area

1986 ◽  
Vol 90 ◽  
pp. 423-437 ◽  
Author(s):  
J. R. G. Hislop
Keyword(s):  
Conclusive Evidence ◽  
Dual Purpose ◽  
Important Species ◽  
Major Species ◽  
Catch Rates ◽  
The 1960S ◽  
Surrounding Areas ◽  
Clyde Sea ◽  
Sea Area ◽  
Principal Species

SynopsisData from the Clyde demersal fishery during the period 1960 to 1984 are presented. Annual landings of demersal species at Chde ports in recent years have ranged from 4000 to 10,000 tonnes, with a first sale value of £2–5 million. In the 1960s the fishery was undertaken mainly by seine-net vessels, but the present fleet consists largely of dual-purpose light/Nephrops trawlers. The demersal fishery is seasonal and during the winter and spring there is an influx of ‘stranger’ vessels. Five species (cod, whiting, saithe, hake and haddock) make up more than 80% of the demersal landings from the Clyde. The landings of saithe have fluctuated very considerably during the period under review. Other relatively important species are dogfish, plaice, skate and ray and angler fish. In general the Clyde fishery represents only a small proportion of the total Scottish landings but in recent years landings of hake from the Clyde grounds have averaged approximately 40% of the Scottish hake total. The Clyde demersal fishery depends to a large extent on young fish and both the total annual landings and the relative importance of the principal species fluctuate from year to year in response to variations in the strength of the recruiting year classes. The catch rates of the principal species vary greatly throughout the year. Although there is no conclusive evidence that the Clyde populations are self-contained, all the major species are known to spawn within or close to the area and tagging experiments have suggested that there may not be much mixing between Clyde fish and those from surrounding areas. This may in part, however, reflect the fact that fishing intensity within the Clyde is high and fish are recaptured before they have had time to leave the area. For management purposes, the Clyde demersal stocks are included in ICES Sub-area VI.

scholarly journals Use of avoidance behaviours to reduce the economic impacts of the EU Landing Obligation: the case study of a mixed trawl fishery

2019 ◽  
Vol 76 (6) ◽  
pp. 1554-1566
Author(s):  
Fabien Pointin ◽  
Fabienne Daurès ◽  
Marie-Joëlle Rochet
Keyword(s):  
Temporal Distribution ◽  
Grid Method ◽  
Fishing Effort ◽  
Economic Losses ◽  
Otter Trawl ◽  
Trawl Fishery ◽  
Nested Grid ◽  
Fishing Practices ◽  
The Eu

Abstract The EU Landing Obligation (LO) is designed to reduce bycatch (i.e. unwanted catch) through more selective fishing practices, such as avoidance behaviours which consist in allocating fishing effort to other species, fishing grounds or seasons. Incentives for fishers to change their behaviours depend on their economic performances as well as their ability to avoid bycatch. Changes in economic performances under the LO are evaluated based on cost and revenue equations. The nested grid method is then used to explore the spatial and temporal distribution of landings and discards, and to suggest alternative effort allocation to avoid bycatch. This article is focussed specifically on the French otter trawl fishery in the eastern English Channel and southern North Sea. Results suggest that under the LO the choke species problem will curtail fishing activities earlier in the year, leading to significant economic losses. In the absence of significant quota top-ups (at least 75%), a change in fishing practices consisting in reducing overall bycatch by 30% is insufficient to reduce losses. With a particular attention to choke species, more economically efficient avoidance strategies can be found thanks to the nested grid method.

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