scholarly journals Age, growth and population structure of jumbo flying squid, Dosidicus gigas, based on statolith microstructure off the Exclusive Economic Zone of Chilean waters

2010 ◽  
Vol 91 (1) ◽  
pp. 229-235 ◽  
Author(s):  
Xinjun Chen ◽  
Huajie Lu ◽  
Bilin Liu ◽  
Yong Chen
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
The Body ◽  
Exclusive Economic Zone ◽  
Spatial And Temporal Variability ◽  
Dosidicus Gigas ◽  
Austral Spring ◽  
Economic Zone ◽  
Austral Autumn ◽  
Jumbo Flying Squid

The jumbo flying squid, Dosidicus gigas, support an important squid fishery off the Exclusive Economic Zone of Chilean waters. However, we only have limited information about their biology. In this study, age, growth and population structure of D. gigas were studied using statoliths from 533 specimens (386 females and 147 males) randomly sampled in the Chinese squid jigging surveys from 2007 to 2008 off the Exclusive Economic Zone of Chile. Mantle lengths (MLs) of the sample ranged from 206 to 702 mm, and their ages were estimated from 150 to 307 days for females and from 127 to 302 days for males. At least two spawning groups were identified, the main spawning peak tended to occur between August and November (austral spring group), and the secondary peak appeared during March to June (austral autumn group). The ML–age relationship was best modelled by a linear function for the austral spring group and a power function for the austral autumn group, and the body weight (BW)–age relationship was best described by an exponential function for both the groups. Instantaneous relative growth rates and absolute growth rates for ML and BW did not differ significantly between the two groups. The growth rate of D. gigas tended to be high at young stages, and then decreased after the sub-adult stage (>180 days old). This study suggests large spatial and temporal variability in key life history parameters of D. gigas, calling for the collection of more data with fine spatial and temporal scales to further improve our understanding of the fishery biology of D. gigas.

scholarly journals Fishery biology of the jumbo flying squid Dosidicus gigas off the Exclusive Economic Zone of Chilean waters

2010 ◽  
Vol 74 (4) ◽  
pp. 687-695 ◽  
Author(s):  
Bilin Liu ◽  
Xinjun Chen ◽  
Huajie Lu ◽  
Yong Chen ◽  
Weiguo Qian
Keyword(s):  
Exclusive Economic Zone ◽  
Dosidicus Gigas ◽  
Fishery Biology ◽  
Economic Zone ◽  
Jumbo Flying Squid

Fine-scale population structure of Lobatus gigas in Jamaica’s exclusive economic zone considering hydrodynamic influences

2018 ◽  
Vol 199 ◽  
pp. 53-62 ◽  
Author(s):  
Kimani A. Kitson-Walters ◽  
Adam S. Candy ◽  
Nathan K. Truelove ◽  
Marcia E. Roye ◽  
Mona K. Webber ◽  
...  
Keyword(s):  
Population Structure ◽  
Exclusive Economic Zone ◽  
Fine Scale ◽  
Scale Population ◽  
Economic Zone

Age, growth and population structure of jumbo flying squid, Dosidicus gigas, off the Costa Rica Dome

2012 ◽  
Vol 93 (2) ◽  
pp. 567-573 ◽  
Author(s):  
Xinjun Chen ◽  
Jianhua Li ◽  
Bilin Liu ◽  
Yong Chen ◽  
Gang Li ◽  
...  
Keyword(s):  
Population Structure ◽  
Costa Rica ◽  
Instantaneous Growth Rate ◽  
Spawning Ground ◽  
Dosidicus Gigas ◽  
Specific Population ◽  
Daily Growth ◽  
Growth Zones ◽  
Costa Rica Dome ◽  
Jumbo Flying Squid

Based on the samples collected in Chinese scientific surveys off the Costa Rica Dome from July to August in 2009, statolith microstructure of the jumbo flying squid, Dosidicus gigas, was analysed for studying their age, growth and population structure. Three typical growth zones (postnuclear, dark and peripheral zones), abnormal increments (checks) and aberrant microstructure (additional centre and additional rings) were found in the statoliths examined. Squid sizes ranged from 205 to 429 mm dorsal mantle length (ML) with ages no more than 10 months for females and 8 months for males. Back-calculated hatching dates were from November 2008 to April 2009. Growth in ML was best described by a linear function for both the sexes, while growth in body weight was best quantified by an exponential function for females and a power curve for males. The maximum absolute daily growth rates and instantaneous growth rate in ML were reached during 181–210 and 151–180 days for females and males, respectively. The Costa Rica Dome and its adjacent waters were considered as a potential spawning ground because of presence of not only high proportion of mature squid but also rhynchoteuthion paralarvae, and high primary productivity from the strong upwelling. This study suggests that D. gigas have complicated intra-specific population structure and large spatial variability in the key life history parameters.

Age, growth and population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters

2001 ◽  
Vol 54 (1) ◽  
pp. 51-61 ◽  
Author(s):  
J. Argüelles ◽  
P.G. Rodhouse ◽  
P. Villegas ◽  
G. Castillo
Keyword(s):  
Population Structure ◽  
Dosidicus Gigas ◽  
Jumbo Flying Squid

scholarly journals Remote sensing of upwelling off Australia's north-east coast

2019 ◽  
Author(s):  
Mochamad Furqon Azis Ismail ◽  
Joachim Ribbe ◽  
Johannes Karstensen ◽  
Vincent Rossi
Keyword(s):  
Continental Shelf ◽  
Fish Larvae ◽  
Trophic Levels ◽  
Western Boundary ◽  
Spatial And Temporal Variability ◽  
Austral Spring ◽  
Ocean Reanalysis ◽  
Chl A ◽  
North East ◽  
Austral Autumn

Abstract. Cross-shelf processes drive the exchange of water between the continental shelf and western boundary currents, leading to the import and export of heat, freshwater, sediments, nutrients, plankton, fish larvae, and other properties. Upwelling is an important process which modulates those exchanges. It regulates primary productivity, which in turn promotes higher trophic levels and fisheries. In this paper, we investigate upwelling events in the East Australian Current (EAC) intensification zone off Southeast Queensland through the analysis of remotely-sensed Chlorophyll-a (Chl-a) and Sea Surface Temperature (SST) as well as wind and ocean reanalysis products. A particular focus is on identifying the likely mechanisms that drive upwelling events during the austral autumn to winter which are evident from cold SST and enhanced Chl-a concentrations. Four complementary Upwelling Indices (UIs) are derived. Chl-a (UIChla) and SST (UISST) based indices characterize the oceanic response to upwelling, while indices based on wind (UIw) and current (UIc) data capture the forcing of upwelling. The spatial and temporal variability of all UIs is examined over the continental shelf. It reveals distinct seasonal patterns. For the northern region, UIs identify the well-known Southeast Fraser Island Upwelling System. It prevails during the austral spring to early summer and is driven by current- and upwelling favourable wind. In contrast, upwelling is enhanced over the southern shelf during austral autumn to winter. About 70 % of all UISST and UIChla identified upwelling events occur during this period. A case study is presented that provides observational evidence for the existence of a shelf-break upwelling. Simultaneous downwelling favourable wind stress and upwelling favourable current-driven bottom stress establish a flow convergence in the bottom boundary layer (BBL). These convergent BBL flows force upwelling of cold and nutrient-rich slope waters as evident from negative SST anomaly and enhanced Chl-a in austral autumn to winter. It is evident from these results that the shelf region is characterised by two distinct seasonally reoccurring upwelling regimes.

scholarly journals Variability of Physical and Biogeochemical Parameters in the Exclusive Economic Zone of Qatar

2021 ◽  
Author(s):  
Aboobacker Valliyil Mohammed ◽  
Fazle Rakib ◽  
Ibrahim M.A.S. Al-Ansari ◽  
Yusuf Sinan Husrevoglu ◽  
Oguz Yigiterhan ◽  
...  
Keyword(s):  
Late Summer ◽  
Exclusive Economic Zone ◽  
Spatial And Temporal Variability ◽  
Strong Wind ◽  
Surface Cooling ◽  
Chl A ◽  
Hypoxic Conditions ◽  
Economic Zone ◽  
Biogeochemical Parameters ◽  
Wind Mixing

The oceanographic data collected along a transect in the Exclusive Economic Zone (EEZ) of Qatar during late summer (September 2014) and winter (January 2015) have been analyzed to investigate the spatial and temporal variability of hydrography and biogeochemistry. The study reveals that stratification is dominant in the deep-water regions during September, with a vertical variation of around 9 °C from surface to bottom. However, the water column remains in homogeneity during January due to strong wind mixing and surface cooling. The dissolved oxygen (DO) in the upper layer of the EEZ is on a reasonable range in both the seasons, while they gradually decrease with respect to depth in the mid and bottom layers during January. This leads to hypoxic conditions in summer. Chlorophyll-a (Chl-a ) is relatively high during summer in the offshore region, while that in the nearshore regions is very low. The variability in the physical and biogeochemical parameters has shown significant effects in primary productivity in the EEZ of Qatar.

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