Reproductive biology of yellowfin tuna in the eastern Australian Fishing Zone, with special reference to the north-western Coral Sea

1991 ◽  
Vol 42 (5) ◽  
pp. 465 ◽  
Author(s):  
GR McPherson
Keyword(s):  
Oocyte Maturation ◽  
Developmental Stages ◽  
Early Morning ◽  
Yellowfin Tuna ◽  
Eastern Coast ◽  
Spawning Frequency ◽  
The North ◽  
Coral Sea ◽  
Tuna Fisheries ◽  
North Western

Developmental stages of oocyte maturation and degenerative stages of postovulatory follicles in yellowfin tuna from the eastern Australian Fishing Zone of the Coral Sea are described. The time of spawning of yellowfin appeared to be during the late evening and early morning. Final oocyte maturation occurred in less than 24 h; postovulatory follicles could not be identified in ovaries after 24 h. Spawning of yellowfin commenced in the north-western Coral Sea by October and had ceased in the central-western Coral Sea by late February. The duration of spawning appeared to be less protracted in the south-western Coral Sea. The average spawning frequency of female yellowfin in the western Coral Sea was once every 1.54 days. Significant differences in spawning frequency were found between different size classes of yellowfin; larger fish spawned more frequently. The spawning stock of yellowfin in the north-western and central-western Coral Sea could be the major source of recruits for the tuna fisheries off the eastern coast of Australia.

Exploitation and movements of yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) tagged in the north-western Coral Sea

1998 ◽  
Vol 49 (6) ◽  
pp. 475 ◽  
Author(s):  
John Hampton ◽  
John Gunn
Keyword(s):  
Seasonal Pattern ◽  
Yellowfin Tuna ◽  
Thunnus Albacares ◽  
Bigeye Tuna ◽  
Catch Per Unit Effort ◽  
The North ◽  
Coral Sea ◽  
Release Area ◽  
Seasonal Signal ◽  
North Western

Yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) were tagged and released in the north-western Coral Sea off northern Queensland in 1991 and 1992. Over the next five years, recaptures were reported by Australian longline vessels based in Cairns and fishing in the release area, and by industrial tuna fleets fishing in the adjacent western Pacific region, thus demonstrating clear links between the tuna stocks in these areas. Some southerly movements of yellowfin, in particular, further suggested links with stocks supporting the longline fishery in the south-eastern Australian Fishing Zone. Bigeye tuna tag returns and catch per unit effort by Cairns-based longliners showed a strong seasonal signal, peaking in mid year. Yellowfin tag-return data displayed a similar, but weaker, seasonal pattern. The data were analysed by use of tag-attrition models with seasonally variable catchability and with two assumptions regarding changes in targeting of the two species by longliners during the study. Under both assumptions, the local exploitation rates for yellowfin are low: about 0.07 in 1996. For bigeye, the local exploitation rate in 1996 may have been as high as 0.30, warranting a cautious approach to further fishery expansion in this area.

scholarly journals Beach Stability on a Tropical Uplifted Coral Atoll:  Niue Island

2021 ◽  
Author(s):  
◽  
Teuvirihei Helene Marsters
Keyword(s):  
Sea Level ◽  
Wave Energy ◽  
Beach Erosion ◽  
Eastern Coast ◽  
Leeward Side ◽  
Composition Analysis ◽  
The North ◽  
Tropical Reef ◽  
North Western ◽  
Reef Platform

<p>Fundamental knowledge about the change and dynamics, and what thresholds drive sediment accumulation in tropical reef settings are poor. Little is also known about how they may respond to the higher and stormier seas that are predicted in an enhanced greenhouse world. Niue's rocky shore setting and the regular occurrence of small isolated pocket-beaches provides an ideal environment to investigate key factors that drive beaches to accumulate or erode within a tropical reef setting. Niue is the largest uplifted coral atoll in the world, covering an area of 200 km^2 and rising to 70 m above sea level. The island is characterised by a series of Pleistocene reef terraces with distinct platforms forming at the base at approximate mean sea level. Lateral reef growth at sea level is juxtaposed with landward retreat of the limestone cliffs leading to the formation of shore platforms. Geomorphological surveys of 9 sites revealed a combined reef platform width of up to 150 m with the widest section found on the leeward side of the island on the north western coast and the narrowest (<30 m) being located on the more exposed south eastern coast. Therefore, their distribution is likely related to the energy environment around the island. Beaches up to 12 m wide and 50 m long are only found in protected coves along the shoreline. Their development is determined by platform width, with beaches only occurring in areas where platform width is more than 60 m. While distance from the reef crest played a role in dissipating wave energy across the platform therefore reducing beach erosion, beach stability is reliant the morphology of the underlying ramp on the landward edge of the platform. Beaches increased in width at higher elevations therefore implying that a higher ramp can effectively reduce the amount of wave energy reaching the landward edge of the beach resulting in the accumulation of sediment. Composition analysis of 51 samples reveal that the Niuean beaches are largely composed of unconsolidated bioclastic sand and gravels derived from the surrounding reef platform. They are characterised by an assemblage of chlorozoan carbonates typical of tropical areas, in which coral and coralline algae are prominent (>50%) except on the north western platforms (Hio and Tuapa) where foraminifera is the key component. Radiocarbon dating further indicates the youth of these beaches returning modern ages for reef flat microatolls as well as the beach sand itself. These sedimentary environments on Niue are therefore intrinsically linked to the platform biota and their preservation also dependent on the frequency of cyclones. The fast recovery of the foraminifera-rich north western beaches following Tropical Cyclone Heta (2004) is an indication that the foraminifera community can re-establish quicker after cyclones. This therefore confirms that the beaches are highly dynamic, and build out or erode during alternated calm and stormy conditions. The close links between beach accumulation and their biotic communities will be strongly affected by human-induced climate change, likely leading to the beaches becoming more ephemeral in the future.</p>

scholarly journals Global earthquakes in the 2021 first half according to the GS RAS

2021 ◽  
Vol 3 (3) ◽  
pp. 7-27
Author(s):  
Yuri Vinogradov ◽  
Marina Ryzhikova ◽  
Natalia Petrova ◽  
Svetlana Poygina ◽  
Marina Kolomiets
Keyword(s):  
Main Shock ◽  
Seismic Energy ◽  
Focal Mechanisms ◽  
Eastern Coast ◽  
Strong Earthquakes ◽  
The North ◽  
The Earth ◽  
Northern Mongolia ◽  
The Russian Federation ◽  
North Western

Data on the 2021 first half Earth seismicity at the level of strong earthquakes with magni-tudes mb6.0 according to the Alert Service of the Geophysical Survey RAS are given. The review also includes information on 81 earthquakes in Russia and adjacent territories, felt in the settlements of the Russian Federation. For 14 strong earthquakes, within one or two days after their occurrence, Informational messages were published, and information about the focal mechanisms was giving. The strongest earthquake of the Earth with MS=7.8 (Mw=8.1) occurred on March 4 at the Kermadec Islands, New Zealand. The largest human casualties and material damage during the study period were caused by catastrophic earth-quakes with MS=5.1 (Mw=5.8) and MS=5.9 (Mw=6.3), which occurred on January 14 at the Sulawesi Island, Indonesia. As a result of the earthquakes, 81 people died, 826 were injured. The strongest earthquake in Russia was the March 16 earthquake with MS=6.7 (Mw=6.6) off the eastern coast of Kamchatka. The maximum shaking intensity in Russia (I=6) was manifested by the strong Khuvsgul earthquake with MS=7.2 (Mw=6.8), which took place on January 11 in the Northern Mongolia, near the border with Russia. The position of the main shock and its aftershocks indicate the intensification of the seismic process in the north-western part of the Khuvsgul rift zone. According to the focal mechanisms of the main shock and two strong aftershocks, the stress of the northwest/southeast extension prevails in this zone, and the predominant slip type along the faults of the northeast strike is a nor-mal fault. The global seismic energy released in the 2021 first half remains, as in the previ-ous two years, at a reduced level, relative to the average for the last 11.5 years, which indi-cates a continuing seismic calm.

scholarly journals First successful breeding of Osprey Pandion haliaetus in Sardinia since 1968

2021 ◽  
Vol 90 (2) ◽  
Author(s):  
Alberto Fozzi ◽  
Roberto Fozzi ◽  
Ilaria Fozzi ◽  
Francesco Guillot ◽  
Gabriella Caria ◽  
...  
Keyword(s):  
Human Disturbance ◽  
First Record ◽  
Eastern Coast ◽  
Western Coast ◽  
Pandion Haliaetus ◽  
The North ◽  
North Western ◽  
Wintering Population

In 2020, a pair of ospreys nested in the north western coast of Sardinia and the successful fledging of two chicks is the first record in the island since 1968. The last reported breeding occurred in the eastern coast of the island and after that the species was considered extinct. Ospreys regularly migrate, estivate and winter in Sardinia, with a wintering population of about 40 individuals in 2018. This new breeding episode is not resulting from reintroduction projects and may be related to the dynamics of the close population of Corsica and to the exceptional absence of human disturbance along the coast due to COVID 19 lock-down.

Short-term movement and behaviour of black marlin Makaira indica in the Coral Sea as determined through a pop-up satellite archival tagging experiment

2003 ◽  
Vol 54 (4) ◽  
pp. 515 ◽  
Author(s):  
John S. Gunn ◽  
Toby A. Patterson ◽  
Julian G. Pepperell
Keyword(s):  
Habitat Preferences ◽  
Diving Behaviour ◽  
Archival Data ◽  
Data Sets ◽  
Data Set ◽  
Daily Movement ◽  
Depth Data ◽  
The North ◽  
Coral Sea ◽  
North Western

Pop-up satellite tags were deployed on seven black marlin, Makaira indica,in the north-western Coral Sea, to examine movement, post-capture mortality and habitat preferences. Five of these tags popped up and transmitted positions, and detailed data on diving behaviour, ambient water temperature and daily movement were received via ARGOS transmission from two tags. One tag was later found on a beach, allowing a complete archival data set to be downloaded and geolocation estimates provided by software on-board the pop-up tags and those based on the complete archival tag data sets to be compared. The tags indicated rapid movement away from release sites; three south-easterly displacements (222 km (120 nm), 222 km (120 nm), and 1185.3 km (640 nm) net) appeared to be associated with the East Australian Current, one moved 555.6 km (300 nm) directly east, and the last tag moved offshore and then back towards the coast over a 2-month period for a net displacement of 384 km (207 nm). Based on displacement speeds and diving behaviour, it was concluded that five of the seven fish survived capture and handling for periods ranging from 3 to 64 days. The fate of the other two is unknown. Estimates of longitude made on board the pop-up tag were very similar to the best estimates that could be made using the complete archival data set; however, pop-up tag latitude estimates were significantly more variable than those using the archival data. In the two cases in which pop-up tags were scheduled to stay on the marlin for more than 3 months, the tags detached prematurely, after 39 and 64 days. Temperature and depth data indicated a preference for waters of the mixed layer (20–120 m) and temperatures warmer than 24°C.

Beach Stability on a Tropical Uplifted Coral Atoll:  Niue Island

2021 ◽  
Author(s):  
◽  
Teuvirihei Helene Marsters
Keyword(s):  
Sea Level ◽  
Wave Energy ◽  
Beach Erosion ◽  
Eastern Coast ◽  
Leeward Side ◽  
Composition Analysis ◽  
The North ◽  
Tropical Reef ◽  
North Western ◽  
Reef Platform

<p>Fundamental knowledge about the change and dynamics, and what thresholds drive sediment accumulation in tropical reef settings are poor. Little is also known about how they may respond to the higher and stormier seas that are predicted in an enhanced greenhouse world. Niue's rocky shore setting and the regular occurrence of small isolated pocket-beaches provides an ideal environment to investigate key factors that drive beaches to accumulate or erode within a tropical reef setting. Niue is the largest uplifted coral atoll in the world, covering an area of 200 km^2 and rising to 70 m above sea level. The island is characterised by a series of Pleistocene reef terraces with distinct platforms forming at the base at approximate mean sea level. Lateral reef growth at sea level is juxtaposed with landward retreat of the limestone cliffs leading to the formation of shore platforms. Geomorphological surveys of 9 sites revealed a combined reef platform width of up to 150 m with the widest section found on the leeward side of the island on the north western coast and the narrowest (<30 m) being located on the more exposed south eastern coast. Therefore, their distribution is likely related to the energy environment around the island. Beaches up to 12 m wide and 50 m long are only found in protected coves along the shoreline. Their development is determined by platform width, with beaches only occurring in areas where platform width is more than 60 m. While distance from the reef crest played a role in dissipating wave energy across the platform therefore reducing beach erosion, beach stability is reliant the morphology of the underlying ramp on the landward edge of the platform. Beaches increased in width at higher elevations therefore implying that a higher ramp can effectively reduce the amount of wave energy reaching the landward edge of the beach resulting in the accumulation of sediment. Composition analysis of 51 samples reveal that the Niuean beaches are largely composed of unconsolidated bioclastic sand and gravels derived from the surrounding reef platform. They are characterised by an assemblage of chlorozoan carbonates typical of tropical areas, in which coral and coralline algae are prominent (>50%) except on the north western platforms (Hio and Tuapa) where foraminifera is the key component. Radiocarbon dating further indicates the youth of these beaches returning modern ages for reef flat microatolls as well as the beach sand itself. These sedimentary environments on Niue are therefore intrinsically linked to the platform biota and their preservation also dependent on the frequency of cyclones. The fast recovery of the foraminifera-rich north western beaches following Tropical Cyclone Heta (2004) is an indication that the foraminifera community can re-establish quicker after cyclones. This therefore confirms that the beaches are highly dynamic, and build out or erode during alternated calm and stormy conditions. The close links between beach accumulation and their biotic communities will be strongly affected by human-induced climate change, likely leading to the beaches becoming more ephemeral in the future.</p>

Arms and Afghans in Makrān: an episode in Anglo-Persian relations 1905–1912

1986 ◽  
Vol 49 (1) ◽  
pp. 8-24 ◽  
Author(s):  
R. M. Burrell
Keyword(s):  
Eastern Coast ◽  
The South ◽  
Military Intelligence ◽  
Naval Blockade ◽  
South Eastern ◽  
The North ◽  
Literary Device ◽  
The Government ◽  
The Military ◽  
North Western

When Kipling published that aptly-named poem ‘Arithmetic on the Frontier’ in 1886 his use of the term ‘jezail’ was no more literary device, for the tribesmen of the north-western borderlands were then armed with locally made, muzzle-loading, smooth-bore muskets. A decade later a few European breech-loading rifles began to appear, and by 1907 the military intelligence department estimated that over a quarter of those tribesmen had acquired a modern weapon. It was the Government of India's wish to halt that flow of arms which led to a British naval blockade of the south-eastern coast of Persia from 1909, and the landing of troops in Makrāan during 1910 and 1911.

scholarly journals On the verge of extinction: a survey of the mangrove finch Cactospiza heliobates and its habitat on the Galápagos Islands

Oryx ◽  
2004 ◽  
Vol 38 (2) ◽  
pp. 171-179 ◽  
Author(s):  
Michael Dvorak ◽  
Hernán Vargas ◽  
Birgit Fessl ◽  
Sabine Tebbich
Keyword(s):  
Habitat Degradation ◽  
Tree Height ◽  
Galapagos Islands ◽  
Eastern Coast ◽  
Western Coast ◽  
Mangrove Forests ◽  
Galápagos Islands ◽  
The North ◽  
North Western ◽  
Habitat Parameters

The Critically Endangered mangrove finch Cactospiza (=Camarhynchus) heliobates is now confined to Isabela Island in the Galápagos Islands and is exclusively found in mangrove forests. Formerly it occurred also on neighbouring Fernandina Island, but is apparently extinct there. The population size and ecology of the species was relatively unknown until 1994. We conducted surveys, habitat assessments and behavioural observations of the species between 1996 and 2000. Although Isabela Island has approximately 760 ha of mangrove forests, breeding was confirmed at only two sites, comprising 32 ha in total, on the north-western coast. Our estimate of the population in these two areas is 100 individuals. Additionally, 3–5 territories (which probably contained breeding individuals) were discovered on the south-eastern coast. A comparison of habitat parameters showed that tree height and amount of dead wood were significantly higher within than outside territories, and these are therefore likely to be important habitat components for this species. As considerable structural differences were detected between the two sites holding the main populations and all other mangrove stands on Isabela, it seems possible that the latter are sub-optimal habitat. We therefore conclude that one of the reasons for the very limited distribution of the species is habitat degradation caused by hitherto unknown factors.

Spawning aggregation of the lanternfish Diaphus danae (family Myctophidae) in the north-western Coral Sea and associations with tuna aggregations

2012 ◽  
Vol 63 (12) ◽  
pp. 1255 ◽  
Author(s):  
Adrian J. Flynn ◽  
John R. Paxton
Keyword(s):  
Gonadosomatic Index ◽  
Spawning Aggregation ◽  
Bigeye Tuna ◽  
The North ◽  
Spawning Aggregations ◽  
Coral Sea ◽  
Thunnus Obesus ◽  
Males And Females ◽  
First Time ◽  
North Western

A spawning aggregation of the lanternfish Diaphus danae in the Coral Sea, that is fed on by spawning aggregations of yellowfin and bigeye tuna, has been sampled by mid-water trawling for the first time. Males and females in the aggregation occurred at a ratio of 23 to 1 and occupied two non-overlapping size classes (males 71.2–95.1-mm standard length (SL), females 99.0–121.4-mm SL). Hydrated oocytes with single oil droplets, which indicated imminent spawning, were in higher proportion in the first trawl (2134 hours to 2234 hours) than in the final trawl (0324 hours to 0424 hours) through the aggregation. Maximum estimated female D. danae fecundity (25 803) and gonadosomatic index (34.01) were higher than for any other lanternfish species recorded. Bigeye tuna (Thunnus obesus) individuals collected from aggregations were estimated to have 81–319 D. danae specimens in their stomachs. The annual Coral Sea D. danae aggregation is the only confirmed lanternfish spawning aggregation in Australian waters. The D. danae spawning aggregation provides a rich, transient foraging resource for spawning bigeye and yellowfin tuna in the Coral Sea, these being the only known tuna spawning aggregations in the Eastern Tuna and Billfish Fishery.

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