World’s largest fish breeding grounds found under the Antarctic ice

2021 ◽  
Vol 50 (SuplEsp) ◽  
pp. 31-40
Author(s):  
Susana Caballero ◽  
Debbie Steel ◽  
Logan Pallin ◽  
Natalia Botero ◽  
Fernando Felix ◽  
...  

We analysed 114 DNA samples collected in different locations within the stock G breeding grounds, including Ecuador and the northern and southern Pacific of Colombia. We genotyped 15 microsatellite loci, sexed all samples, and performed genotype comparisons. Genotype comparisons were done using a DNA register of previously genotyped individuals from the Colombian breeding ground and the Antarctic Peninsula feeding Area. We confirmed connectivity between feeding grounds in Antarctic Peninsula and breeding grounds in Colombia and Ecuador using microsatellite loci. We found recaptures within each sampling location in the same year, but we also found a few recaptures in the same locations between years both in breeding and feeding grounds. Interestingly, we found recaptures between breeding and feeding grounds using samples collected 20 years apart, providing some information about longevity in this stock. Further comparisons with other data sets (Brazil, North Pacific) are needed to understand the migratory connectivity of this stock.


2020 ◽  
Vol 29 (1) ◽  
pp. 111-121
Author(s):  
K.N.O. Bob-Manuel ◽  
A. Ugbomeh ◽  
O. Taylorharry

The effects of sub-lethal concentrations of Corexit 9500 on growth and condition factor of juveniles of Clarias gariepinus was investigated after 21days, in 2018. 160 fishes were used as test organisms with a loading of 10/treatment and were exposed to 0.00, 0.0125, 0.025 and 0.05 ml/L concentrations of Corexit 9500. Treatments were in triplicate and Complete Randomised Design was adopted. The growth in length and weight of C. gariepinus was significantly higher in the control than the test treatments (P<0.05). The increase in weight of the control was significantly different from the three treatments. Temperature was not significantly different (P>0.05); however, the DO of control was significantly higher (P < 0.05) than that of the treatments, with the lowest DO in the 0.05ml/l treatment. pH was acidic for all treatments including the control but was more acidic with increasing concentration of Corexit 9500. The pH value for each treatment was significantly different (P<0.05). The conductivity was significantly different from each other (P<0.05) with higher values at the 0.025 ml/L concentrations. The condition factor (K) decreased with increasing toxicant concentration and was significantly different (P<0.05) at 0.0125ml/L and at Weeks 2 and 3 of 0.05 ml/L. Corexit 9500 dispersants should be appropriately assessed before deployment, and their use near fish breeding grounds should be avoided. Key words: Clarias gariepinus, dispersant, growth, physicochemical parameters, sub-lethal


1990 ◽  
Vol 2 (4) ◽  
pp. 285-285
Author(s):  
K. Birkenmajer

During the past 30 years or so, the primary objects of environmental protection in Antarctica were living organisms such as penguins and seals, and their breeding grounds, terrestrial plants and their habitats. The ever growing threats to the icy continent, resulting from increasing human activities, lead SCAR, the Antarctic Treaty Consultative Parties (ATCPs), and recently also the Council of Managers of National Antarctic Programmes (COMNAP) to seek improved measures for conservation of the Antarctic fauna and flora, to actively participate in the preparation of conventions for protection of seals and other marine living organisms, and to elaborate a mandatory code for waste disposal.


2020 ◽  
Author(s):  
Nicholas Outa ◽  
Edna Waithaka

Fish stocks over exploitation and excessive water abstraction in Lake Naivasha have caused drastic changes in the lake’s ecosystem and fisheries. As a result of this, measures were taken by concerned stakeholders to protect and safe guard the fragile lake ecosystem. A study was conducted on the lake’s fishery to identify fish critical habitats and recommended for their protection through a participatory approach. These identified habitats formed the four protected areas in addition to the shoreline area. Gill net surveys are routinely conducted at nine sampling sites spread to cover the whole lake. In the study, six fish species were recorded at breeding and non-breeding grounds of the lake during the sampling period. Oreochromis niloticus was the most abundant species accounting for 72.1% and 56.6% of fish in breeding and non-breeding grounds respectively. Size frequency data revealed that the majority of C. carpio in breeding grounds ranged between 24 and 36 cm whereas in non-breeding areas, they are slightly smaller, majority of individuals ranging between 23 and 32 cm. The number of male fish was generally higher than that of females giving a sex ratio &gt;1 in both breeding and fishing areas. With the exception of O. leucostictus which recorded 64% and 55% in fishing and breeding areas respectively, the spawning biomass was higher in breeding areas than in fishing areas. Protected fish breeding grounds still remain important as fish spawning and nursery grounds. Activities of monitoring and surveillance need to be strengthened in a spirit of shared responsibility and co-management.


1987 ◽  
Vol 65 (5) ◽  
pp. 1289-1291 ◽  
Author(s):  
Eric P. Hoberg

Specimens of the pentastome Reighardia sternae (Diesing, 1864) are reported for the first time in avian hosts from Antarctica. Mature female specimens were found in a southern black-backed gull (Larus dominicanus Lichtenstein) (1 of 21 examined) while an immature female was found in a south polar skua (Catharacta maccormicki (Saunders)) (1 of 20). Species of Reighardia have not previously been reported among any of the Stercorariinae. The degree of development of individuals of R. sternae provided evidence that the life cycle of this pentastome could be completed on the breeding grounds of its hosts in the region of the Antarctic Peninsula.


1994 ◽  
Vol 21 (3) ◽  
pp. 293 ◽  
Author(s):  
PJ Corkeron ◽  
M Brown ◽  
RW Slade ◽  
MM Bryden

Humpback whales, Megaptera novaeangliae, of the Antarctic Area V stock, pass through Hervey Bay, Queensland, during their southward migration. As part of an investigation of the impact of commercial whalewatching in the bay, aerial surveys were conducted during the 1988-90 whalewatching seasons, and a photo-identification project was run over the 1988 season. In 1988,60 pods containing 127 whales were observed. All pods were sighted on the transects in the eastern section of Hervey Bay, so surveys in 1989 and 1990 were confined to this area. In 1989, 223 whales in 121 pods were counted, and in 1990, 105 whales in 60 pods were observed. There was annual variation in the temporal pattern of the migration through Hervey Bay. Pods tended to occur in shallow water close to the western coast of Fraser Island and, on days when several whales were observed in the bay, pods were not distributed in a regular fashion. Mother-calf pods were the final cohort to migrate through the Bay. The recorded sizes of whale pods varied between observation platforms and averaged 1.75-2.81. In all, 100 whales were identified from photographs of natural marks. Most were photographed once only, although individual whales were sighted up to seven times. Of the 34 whales identified on more than one occasion, 24 were observed over a one- or two-day period. Pod sizes and residence times of whales in Hervey Bay resemble those of whales recorded at tropical breeding grounds. However, there are no data suggesting that Hervey Bay is of particular importance to any class of the humpback whale population migrating off the eastern coast of Australia.


2020 ◽  
pp. 275-282
Author(s):  
Claire Garrigue ◽  
Rochelle Constantine ◽  
Michael Poole ◽  
Nan Hauser ◽  
Phil Clapham ◽  
...  

The movement of individual humpback whales between regional breeding grounds of Oceania (South Pacific) was documented by individualidentification photographs collected from 1999 to 2004. Photographs were collected with comparable effort across the six years in four primaryisland breeding grounds: New Caledonia, Tonga (Vava’u) the Cook Islands and French Polynesia (Mo’orea and Rurutu); with smaller effort inadjacent regions: Vanuatu, Fiji, Samoa, Niue and American Samoa. Interchange among wintering grounds was assessed first with all usablephotographs included in each regional catalogue, representing 1,080 regional sightings (including within-region and between-region resightings)of 949 individual whales from Oceania. From this, 28 cases of movement between (mostly adjacent) regions were documented. Previouslyundocumented interchange was found between regions of central Oceania and the western South Pacific. No individual was sighted in more thantwo regions during this six-year period. The documented movement between regions was one-directional, except for one individual sighted first inFrench Polynesia, then in American Samoa and then back in French Polynesia (each in different years). Only one whale was resighted in more thanone region during the same winter season. No directional trend was apparent and movement between regions did not seem to be sex specific. Asystematic quality control review of all catalogues was then implemented to calculate standardised indices of within-region return and betweenregion interchange, resulting in a quality controlled catalogue of 776 regional sightings of 659 individuals. The standardised indices confirmed thatthe probability of between-region interchange was low, relative to within-region return, supporting the assumption of multiple management unitsor stocks in Oceania. The relative isolation of breeding regions and the movement of individuals across the longitudinal borders of Antarcticmanagement Areas V and VI has important implications for the allocation of historical catches from the Antarctic and therefore, for assessingcurrent levels of recovery for breeding stocks


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