scholarly journals Timing and route of migration of mature female blue crabs in a tidal estuary

2015 ◽  
Vol 11 (5) ◽  
pp. 20140936 ◽  
Author(s):  
David B. Eggleston ◽  
Erika Millstein ◽  
Gayle Plaia
Keyword(s):  
Marine Reserves ◽  
River Estuary ◽  
Mature Female ◽  
Blue Crabs ◽  
White Oak ◽  
Spawning Grounds ◽  
Migration Patterns ◽  
Valuable Data ◽  
Spawning Stock ◽  
Passive Acoustic

Information on migration patterns is critical to using no-take migratory corridors and marine reserves to protect the spawning stock of commercially exploited species. Both active and passive acoustic tracking methods quantified movement of commercially and ecologically important blue crabs in the White Oak River estuary, NC, USA. We targeted post-mating female crabs migrating down-estuary to oceanic spawning grounds. Crabs travelled approximately 14.1 km mainly in deeper channels and over 12–26 days from mating areas to spawning grounds. No crabs were detected migrating down-estuary in the autumn and only 30% were detected migrating down-estuary in spring. None of the crabs detected near spawning grounds were detected or recaptured back up-estuary, suggesting that they either (i) do not return to the estuary after a one to two week period in the spawning area or (ii) were captured by fishermen. The results from this study demonstrate that (1) acoustic transmitters coupled with passive acoustic receivers provided reliable and valuable data on migration patterns of mature female blue crabs and (2) mature female blue crabs are capable of migrating primarily within deep channels to spawning grounds shortly after insemination.

scholarly journals Response to Environmental Factors of Spawning Ground in the Pearl River Estuary, China

2021 ◽  
Vol 9 (7) ◽  
pp. 763
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen ◽  
Ruirui Hu
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Pearl River ◽  
Spawning Ground ◽  
Spawning Grounds ◽  
Chl A ◽  
The Pearl River Estuary ◽  
The Pearl River

Spawning grounds are important areas for fish survival and reproduction, and play a key role in the supplement of fishery resources. This study investigated environmental effects on the spatiotemporal variability of spawning ground in the Pearl River Estuary (PRE), China, using the generalized additive model (GAM), based on satellite remote sensing (sea surface temperature (SST), chlorophyll-a concentration (Chl-a), sea surface salinity (SSS), depth), and in situ observations. Results showed that 39.8% of the total variation in fish egg density was explained by these factors. Among them, the most important factor was SST, accounting for 14.3%, followed by Depth, SSS, and Chl-a, with contributions of 9.7%, 8.5%, and 7.3%, respectively. Spawning grounds in the PRE were mainly distributed in the waters with SST of 22 °C, depth of 30–50 m, SSS of 16–35 ‰, and Chl-a of 6–15 mg/m3. From spring to summer, the spawning ground moved from the outlet of the PRE to the east. The distribution of the spawning ground in the PRE was mainly affected by the Pearl River Plume (PRP), Guangdong Coastal Current (GCC), and monsoons in this area.

scholarly journals Genomic inference of the metabolism of cosmopolitan subsurface Archaea, Hadesarchaea

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Brett J. Baker ◽  
Jimmy H. Saw ◽  
Anders E. Lind ◽  
Cassandre Sara Lazar ◽  
Kai-Uwe Hinrichs ◽  
...  
Keyword(s):  
South African ◽  
Hot Spring ◽  
River Estuary ◽  
Nitrite Reduction ◽  
White Oak ◽  
Physiological Mechanisms ◽  
Subsurface Biosphere ◽  
Metabolic Characteristics ◽  
Sister Clade ◽  
Phylogenomic Analyses

Abstract The subsurface biosphere is largely unexplored and contains a broad diversity of uncultured microbes1. Despite being one of the few prokaryotic lineages that is cosmopolitan in both the terrestrial and marine subsurface2–4, the physiological and ecological roles of SAGMEG (South-African Gold Mine Miscellaneous Euryarchaeal Group) Archaea are unknown. Here, we report the metabolic capabilities of this enigmatic group as inferred from genomic reconstructions. Four high-quality (63–90% complete) genomes were obtained from White Oak River estuary and Yellowstone National Park hot spring sediment metagenomes. Phylogenomic analyses place SAGMEG Archaea as a deeply rooting sister clade of the Thermococci, leading us to propose the name Hadesarchaea for this new Archaeal class. With an estimated genome size of around 1.5 Mbp, the genomes of Hadesarchaea are distinctly streamlined, yet metabolically versatile. They share several physiological mechanisms with strict anaerobic Euryarchaeota. Several metabolic characteristics make them successful in the subsurface, including genes involved in CO and H2 oxidation (or H2 production), with potential coupling to nitrite reduction to ammonia (DNRA). This first glimpse into the metabolic capabilities of these cosmopolitan Archaea suggests they are mediating key geochemical processes and are specialized for survival in the subsurface biosphere.

scholarly journals BOFFFFs: on the importance of conserving old-growth age structure in fishery populations

2013 ◽  
Vol 71 (8) ◽  
pp. 2171-2185 ◽  
Author(s):  
Mark A. Hixon ◽  
Darren W. Johnson ◽  
Susan M. Sogard
Keyword(s):  
Age Structure ◽  
Marine Reserves ◽  
Effective Means ◽  
Old Growth ◽  
Young Females ◽  
Fisheries Science ◽  
Hedging Strategies ◽  
Spawning Stock ◽  
Broad Variety ◽  
Treat All

Abstract The value of big old fat fecund female fish (BOFFFFs) in fostering stock productivity and stability has long been underappreciated by conventional fisheries science and management, although Hjort (1914) indirectly alluded to the importance of maternal effects. Compared with smaller mature females, BOFFFFs in a broad variety of marine and freshwater teleosts produce far more and often larger eggs that may develop into larvae that grow faster and withstand starvation better. As (if not more) importantly, BOFFFFs in batch-spawning species tend to have earlier and longer spawning seasons and may spawn in different locations than smaller females. Such features indicate that BOFFFFs are major agents of bet-hedging strategies that help to ensure individual reproductive success in environments that vary tremendously in time and space. Even if all else were equal, BOFFFFs can outlive periods that are unfavourable for successful reproduction and be ready to spawn profusely and enhance recruitment when favourable conditions return (the storage effect). Fishing differentially removes BOFFFFs, typically resulting in severe truncation of the size and age structure of the population. In the worst cases, fishing mortality acts as a powerful selective agent that inhibits reversal of size and age truncation, even if fishing intensity is later reduced. Age truncation is now known to destabilize fished populations, increasing their susceptibility to collapse. Although some fisheries models are beginning to incorporate maternal and other old-growth effects, most continue to treat all spawning-stock biomass as identical: many small young females are assumed to contribute the same to stock productivity as an equivalent mass of BOFFFFs. A growing body of knowledge dictates that fisheries productivity and stability would be enhanced if management conserved old-growth age structure in fished stocks, be it by limiting exploitation rates, by implementing slot limits, or by establishing marine reserves, which are now known to seed surrounding fished areas via larval dispersal. Networks of marine reserves are likely to be the most effective means of ensuring that pockets of old-growth age structure survive throughout the geographic range of demersal species.

scholarly journals STATE OF STOCKS AND MODERN FISHERY OF ATKA MACKEREL PLEUROGRAMMUS MONOPTERYGIUS (PALLAS, 1810) IN THE OLYUTORSKY-NAVARINSKY AREA OF THE BERING SEA

2020 ◽  
Vol 200 ◽  
pp. 38-57
Author(s):  
A. O. Zolotov ◽  
O. G. Zolotov ◽  
Yu. K. Kurbanov
Keyword(s):  
Bering Sea ◽  
Gulf Of Alaska ◽  
Aleutian Islands ◽  
Commander Islands ◽  
Spawning Grounds ◽  
Spawning Stock ◽  
Atka Mackerel ◽  
Pleurogrammus Monopterygius ◽  
Commercial Stock ◽  
The Bering Sea

Atka mackerel Pleurogrammus monopterygius is one of the mass species of fam. Hexagrammidae that inhabits the boreal and subarctic waters of the North Pacific and forms two large populations in its western and eastern parts. Reproductive range of the eastern, Aleutian population extends from the Gulf of Alaska, along Aleutian Islands to Commander Islands, with the main spawning grounds at the Aleutians and in the southeastern Bering Sea. From these areas, the fish at early stages of ontogenesis spread widely in system of the Bering Sea currents to the western-southwestern Bering Sea, where the atka mackerel aggregations are formed on the external shelf at prominent capes, as Cape Olyutorsky. Dynamics of the atka mackerel stock in the Olyutorsky-Navarinsky area in 1994–2019 is presented on the base of bottom trawl surveys, fishery statistics, and open NOAA data. After the period of low stock in the middle 1990s, the atka mackerel abundance increased sharply to the maximum in 2006–2008, when the spawning stock in this area was about 9.5 . 103 t and the commercial stock about 14.0 . 103 t. Since that time, trend to decreasing is observed, with the spawning stock 3.6 . 103 t and the commercial stock 5.6 . 103 t in 2013, and recent stabilization at the low level with slight decline continuing. A possible reason of the sharp increase in 2000s could be the intensive transport of the atka mackerel juveniles from the main spawning grounds at Aleutian Islands to the area at Cape Olyutorsky. The catches of atka mackerel in the Olyutorsky-Navarinsky area in 1994–2018 corresponded well with its stock dynamics.

scholarly journals Fisheries change spawning ground distribution of northeast Arctic cod

2009 ◽  
Vol 6 (2) ◽  
pp. 261-264 ◽  
Author(s):  
Anders Frugård Opdal
Keyword(s):  
Barents Sea ◽  
Size Structure ◽  
Sudden Increase ◽  
Spawning Grounds ◽  
Norwegian Coast ◽  
Trawl Fishery ◽  
Climatic Variations ◽  
The Barents Sea ◽  
Spawning Stock

Prior to the 1920s, the northeast Arctic (NA) cod were caught at spawning grounds ranging from the southernmost to the northernmost parts of the Norwegian coast, but have for the last 50 yr mainly been caught around the Lofoten archipelago and northwards. The NA cod have their feeding and nursery grounds in the Barents Sea, and migrate south towards the Norwegian coast in the winter to spawn. This study uses commercial fisheries' data from landing ports along the entire Norwegian coast during the period 1866–1969 as evidence of long-term truncation and northerly shift of spawning grounds. Nearly all spawning grounds south of Lofoten have been abandoned, while an increasing proportion of the spawning stock only uses the northernmost areas of the Norwegian coast, Troms and Finnmark. The truncation can hardly be attributed to long-term climatic variations, but may result from an intensive size-selective trawl fishery in the Barents Sea causing a sudden increase in fishing mortality, probably altering the size structure and migratory capacity of the stock.

scholarly journals Long-term changes of abundance and population structure for sockeye salmon in Lake Dalneye (southeastern Kamchatka)

2021 ◽  
Vol 201 (2) ◽  
pp. 324-339
Author(s):  
N. M. Vetsler ◽  
V. F. Bugaev
Keyword(s):  
Sockeye Salmon ◽  
Visual Assessment ◽  
Zooplankton Biomass ◽  
The Body ◽  
Published Data ◽  
Commercial Fishing ◽  
Spawning Grounds ◽  
Spawning Stock ◽  
Anadromous Migration

Effects of interannual fluctuations of sockeye salmon escapement to the spawning grounds on dynamics of sexual, age and length-weight structure of the population are demonstrated on generalized data of long-term observations in Lake Dalneye in 1939–2020. Mature sockeye specimens were caught in the Dalnaya River during their anadromous migration to the lake and analyzed by the authors, personally; archive and earlier published data were used, as well. The escapement was evaluated by visual assessment of the sockeye migrants entered to Lake Dalneye and confirmed by counting of mature individuals on the littoral spawning grounds in the lake. Number of dwarf sockeye salmon was estimated using the earlier found correlation between their stock and forage zooplankton biomass (Kurenkov, 1991; Pogodaev, Kurenkov, 2012). The zooplankton biomass was assessed on samples of zooplankton collected monthly at a stationary station in the central part of the lake (once a month during the ice period and up to three times per month during the ice-free period) from the layer 0–50/55 m by vertical towing of Juday plankton net (mouth diameter 18 cm). The numbers of anadromous sockeye males and females had ratio 1 : 1 in years with the maximum spawning stock, but < 1 : 1 when their returns to the lake decreased. Besides, the males were smaller in such years and the dwarfs (matured without migration to the sea) and jacks (matured with short marine period) were able to escape commercial fishing gears. Age of the spawners had a tendency to increase with decreasing of spawning runs and, conversely, more abundant runs were formed by younger spawners. Long-term pressure from fishery and selection of larger individuals caused the body length and weight decreasing for mature sockeye salmon, shortening of their period of marine feeding, and increasing of the smallsized males portion in the population.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Large Scale ◽  
Average Length ◽  
The United States ◽  
Mature Female ◽  
Science Center ◽  
Fisheries Science ◽  
Spawning Stock ◽  
Average Size ◽  
Peak Abundance ◽  
High Catch Rate

Abstract.—Following intense harvests by distant-water fleets before 1975, populations of spiny dogfish Squalus acanthias in the Northwest Atlantic increased steadily in abundance during the mid-1970s and 1980s. Peak abundance in the early 1990s was short-lived as the United States commercial fleet began a large-scale fishery on mature female dogfish. Between 1989 and 1999, approximately 250,000 metric tons of female spawning stock was removed, reducing the stock to about 30% of B<sub>MSY</sub> levels. Abundance of male dogfish, however, was relatively unaffected by the fishery. The average size of mature female dogfish declined by more than 10 cm and the average length of juveniles declined as well. Recruitment during 1997 to 2003 was the lowest in the 1968–2006 time series. Recruitment in 2006 was low despite a very high catch rate of mature females in the spring survey by the Northeast Fisheries Science Center. The ratio of mature male to females increased from about 2:1 prior to the directed fishery to about 7:1 by 2001.

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