134 resultados para ESTUARIES
Resumo:
In this note we describe the re-formation of a spawning aggregation of mutton snapper (Lutjanus analis). A review of four consecutive years of survey data indicates that the aggregation may be increasing in size. Mutton snapper are distributed in the temperate and tropical waters of the western Atlantic Ocean from Florida to southeastern Brazil (Burton, 2002). Juveniles and subadults are found in a variety of habitats such as vegetated sand bottoms, bays, and mangrove estuaries (Allen, 1985). Adults are found offshore on coral reefs and other complex hardbottom habitat. They are solitary and wary fish, rarely found in groups or schools except during spawning aggregations (Domeier et al., 1996). Spawning occurs from May through July at Riley’s Hump (Domeier et al., 1996) and peaks in June, as indicated by gonadosomatic indices (M. Burton, unpubl. data). Mutton snapper are highly prized by Florida fishermen for their size and fighting ability, and the majority of landings occur from Cape Canaveral, through the Florida Keys, including the Dry Tortugas (Burton, 2002).
Resumo:
Morphological development of the larvae and small juveniles of estuary perch (Macquaria colonorum) (17 specimens, 4.8−13.5 mm body length) and Australian bass (M. novemaculeata) (38 specimens, 3.3−14.1 mm) (Family Percichthyidae) is described from channel-net and beach-seine collections of both species, and from reared larvae of M. novemaculeata. The larvae of both are characterized by having 24−25 myomeres, a large triangular gut (54−67% of BL) in postflexion larvae, small spines on the preopercle and interopercle, a smooth supraocular ridge, a small to moderate gap between the anus and the origin of the anal fin, and distinctive pigment patterns. The two species can be distinguished most easily by the different distribution of their melanophores. The adults spawn in estuaries and larvae are presumed to remain in estuaries before migrating to adult freshwater habitat. However, larvae of both species were collected as they entered a central New South Wales estuary from the ocean on flood tides; such transport may have consequences for the dispersal of larvae among estuaries. Larval morphology and published genetic evidence supports a reconsideration of the generic arrangement of the four species currently placed in the genus Macquaria.
Resumo:
Oysters, Crassostrea virginica, and softshell clams, Mya arenaria, along the Massachusetts coast were harvested by European colonists beginning in the 1600’s. By the 1700’s, official Commonwealth rules were established to regulate their harvests. In the final quarter of the 1800’s, commercial fishermen began harvesting northern quahogs, Mercenaria mercenaria, and northern bay scallops, Argopecten irradians irradians, and regulations established by the Massachusetts Legislature were applied to their harvests also. Constables (also termed wardens), whose salaries were paid by the local towns, enforced the regulations, which centered on restricting harvests to certain seasons, preventing seed from being taken, and personal daily limits on harvests. In 1933, the Massachusetts Legislature turned over shellfisheries management to individual towns. Local constables (wardens) enforced the rules. In the 1970’s, the Massachusetts Shellfish Officers Association was formed, and was officially incorporated in 2000, to help the constables deal with increasing environmental problems in estuaries where fishermen harvest mollusks. The constables’ stewardship of the molluscan resources and the estuarine environments and promotion of the fisheries has become increasingly complex.
Resumo:
North Carolina fishery managers are considering methods to offer greater protection to the blue crab, Callinectes sapidus, spawning stock while maintaining a viable commercial fishery for female blue crabs in high salinity estuaries. We tested how effectively wire rectangles, or excluders, of two internal sizes, 45x80 mm and 45x90 mm, would prevent entry of ovigerous female (sponge) crabs into pots relative to control pots (without excluders) while maintaining sizes and catch rates of male and nonsponged female hard crabs. Field sampling among three pot designs (two excluder sizes and control pots) was conducted in Core Sound, N.C., during 2004–06. Median sizes (carapace widths) of mature female crabs were not different among the three pot types. However, median sizes of male crabs and sponge crabs were greater in control pots than pots with either size of excluder. Catch rates of mature female crabs from control pots were greater than from pots with 45x85 mm excluders. Catch rates of legal male and sponge crabs from control pots were greater than from pots with either size of excluder. Results indicate that using excluders involves a tradeoff between reducing catches and sizes of sponge crabs while also reducing sizes and catches of legally harvestable nonsponge crabs; moreover, the reduction in total catch and sizes would be greater for legal male crabs than for legal nonsponged female crabs. In high salinity waters close to North Carolina’s existing no-harvest blue crab sanctuaries, where females typically dominate catches of hard crabs, the benefit of using excluders to prevent entry of sponge crabs may outweigh a potentially modest decrease in landings of nonsponged females.
Resumo:
One particular habitat type in the Middle Atlantic Bight is not well recognized among fishery scientists and managers, although it is will known and used by recreational and commercial fisheries. This habitat consists of a variety of hard-surface, elevated relief "reef" or reef-like environments that are widely distributed across the predominantly flat or undulating, sandy areas of the Bight and include both natural rocky areas and man-made structures, e.g. shipwrecks and artificial reefs. Although there are natural rock and shellfish reefs in southern New England coastal waters and estuaries throughout the Bight, most reef habitats in the region appear to be man-made reef habitat modification/creation may be increasing. Very little effort has been devoted to the study of this habitat's distribution, abundance, use by living marine resources and associated biological communities (except on estuarine oyster reefs) and fishery value or management. This poorly studied and surveyed habitat can provide fish refuge from trawls and can be a factor in studies of the distribution and abundance of a variety of reef-associated fishery resources. This review provides a preliminary summary of information found on relative distribution and abundance of reef habitat in the Bight, the living marine resources and biological communities that commonly use it, threats to this habitat and its biological resources, and the value or potential value of artificial reefs to fishery or habitat and its biological resources, and the value or potential value of artificial reefs to fishery or habitat managers. The purpose of the review is to initiate an awareness among resource managers about this habitat, its role in resource management, and the need for research.
Resumo:
PREFACE: Four species of menhaden, Brevoortia spp., are found along the Atlantic and Gulf of Mexico coasts of the United States. The Atlantic menhaden, B. tyrannus, is found from Nova Scotia, Can., to West Palm Beach, Fla.; the yellowfin menhaden, B. smithi, is found from Cape Lookout, N. C., to the Mississippi River Delta, La.;the Gulf menhaden, B. patronus, is found from Cape Sable, Fla., to Veracruz, Mex.; and the finescale menhaden, B. gunteri, is found from the Mississippi River Delta, La., to Campeche, Mex. Menhaden are euryhaline species that inhabit coastal and inland tidal waters. Spawning occurs principally at sea (in northern areas some spawning occurs in bays and sounds). Eggs hatch at sea and the larvae are moved to estuaries by ocean currents where they metamorphose and develop as juveniles.
Resumo:
Raritan Bay is the body of water bounded by New York and New Jersey and lying immediately south of New York City (Fig. 1). It has close proximity to the most concentrated urban and industrial area in the United States. Its history has been one of extensive multiple use by the surrounding human population. Dating from the precolonial and colonial periods, people have employed many types of gear to catch and gather its once abundant fishes and shellfishes. Its beaches were once popular for sun bathing and swimming, but after the 1940's they were essentially abandoned because the water became too polluted. Another large use has been for pleasure boating and the transit and dockage of merchant, passenger, and military vessels. Channels and basins were dug in the bay, bulkheads and jetties were constructed along its shores, and it was a donor source of sand and gravel for construction projects. It has also been a receptor for large quantities of domestic and industrial wastes and, mainly for this reason, it is one ofthe most deteriorated estuaries in the United States.
Resumo:
The foraging ecology of bottlenose dolphins Tursiops truncatus in the Northwest Florida Panhandle and estuaries in northern Georgia was determined using diet analysis and behavioral surveys. Stomach content analysis was completed on bottlenose dolphins(N = 25) that stranded in the Northwest Florida Panhandle from November 2006 to March 2009. The most abundant prey species were spot Leiostomus xanthurus (20.4%), squid (10.9%), pinfish Lagodon rhombiodes (10.3%), and Atlantic croaker Micropogonias undulatus (8.5%). Dolphins that stranded during months with a red tide Karenia brevis bloom consumed more pinfish, and spot; whereas dolphins that stranded in non-bloom months consumed more squid, Atlantic croaker, and silver perch Bairdiella chrysoura. Differences in diet were also identified for dolphins that stranded inside bays/sound and dolphin that stranded outside of bays along the coast, and male and female dolphins. Surveys were conducted from south of the Savannah River to north of Ossabaw Sound in Georgia where foraging behaviors were classified. Multivariate Generalized Additive Models were used to test correlations of behaviors to dolphin group size, depth, salinity, temperature, creek width, and tide. Sightings with headstands (p = 0.009), hard stops (p = 0.019), chasing (p = 0.004), mudbank whacking (p < 0.001), herding/circling (p = 0.024), and strand feeding (p = 0.006) were correlated with shallow water or small creeks. Sightings with kerplunking (p = 0.031), mudbank whacking (p = 0.001), strand feeding (p = 0.003), and herding/circling (p = 0.026) were significantly correlated with low tide. The results of the Savannah, Georgia study were the first to characterize foraging behaviors in this area and demonstrate how bottlenose dolphins utilize the salt marsh estuary in terms of foraging. Studies like these are important to determine how dolphins forage efficiently and to provide background information on diet and foraging behavior for use in monitoring future impacts to dolphins in the Northwest Florida Panhandle and near Savannah, Georgia.
Resumo:
This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 9th December 1974. The report looks at information on the Water Bailiffs establishment, including the organisation and the duties of both the Fisheries Inspector and the Senior Bailiff. It also covers the comments from the Regional Fisheries Officer on the report on 'Coarse Fisheries', and the report by the Unit Fisheries Officer on fisheries activities. This looks at coarse fish salvage and stocking, fisheries management, biological work carried out, which include initial studies of the utilisation of sonic tagging methods in the monitoring of salmon in estuaries, fish mortalities, and the fish monitoring figures for areas on the Rivers Lune and Leven. The last section looks at bank erosion on the River Lune. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the South and West Cumberland Fisheries Advisory Committee meeting, which was held on the 28th March, 1977. The report contains sections on fisheries income and expenditure, licensing of salmon dealers, sea patrol of estuaries, proposed fish pass at Branthwaite Weir, and fisheries activities. The section on sea patrol of estuaries looks at the possibility of bailiffs in Derwent, Ehen/Calder and Esk estuaries carrying out sea patrols in places where salmon netting takes place. The section on fisheries activities includes information on the spawning season in 1976; salmon and sea trout catches; restocking and fisheries investigations regarding water quality. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the Regional Fisheries Advisory Committee meeting, which was held on the 31st January, 1983. The report contains sections on Draft net licences (Rivers Derwent and Ellen estuaries), net limitation order, proposed pike ranching scheme on Esthwaite Water, Diseases of fish bill, outbreak of Whirling disease, and the control of federal mink. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the history of contamination in sediments from the Mersey Estuary: Development of a chronology for the contamination of the Mersey Estuary by heavy metals and organochlorines Report produced by the Environment Agency in 1998. This report looks at the history of industrial contamination of the Mersey and Ribble Estuaries back to the early part of the last century, many decades before the start of monitoring programmes providing a remarkably detailed picture of very complex changes. There is a clear record in the sediment of the contamination by each heavy metal (including: Cu, Cr, Hg, Pb, Zn) and organochlorine chemical (including DDT isomers and PCB congeners) studied. The results of the study clearly show the increases in levels of contamination as industry expanded early last century followed by various improvements as this century progressed. Each pollutant has its own idiosyncratic pattern of change with some improvements predating modern environmental concerns whilst other changes seem to relate directly to recent improvements in legislative control. Overall, for the pollutants studied, the results clearly demonstrate the magnitude of improvement that has been achieved in what was a very polluted area. The only major reservation to this story is that despite the wide range of substances covered, many other potentially important pollutants remain to be studied in a similar manner.
Resumo:
The Third National Fisheries Governance Dialogue was a direct follow up on the Second National Fisheries Governance Dialogue held in Elmina in April 2012. It was agreed at the Second dialogue that co-management was the way forward for sustaining Ghana’s fisheries and that its success would depend on a supportive legal framework. The two day dialogue meeting consisted of four key presentations focusing on: the current status of fisheries in Ghana; co-management as a fresh approach to fisheries; outcomes from the regional stakeholder consultations on co-management structure; and outcomes from the research on the legal framework. The presentations were followed by four breakout groups that generated ideas for co-management structures for different species namely pelagic fish or Sardinella, near shore demersal, Volta lake, and lagoons and estuaries. Key elements for co-management structures and elements of a co-management legal framework were later identified during plenary discussions.
Resumo:
We documented inshore spawning of the recreationally important cobia (Rachycentron canadum) in Port Royal Sound (PRS) and St. Helena Sound (SHS), South Carolina, during the period from April to June in both 2007 and 2008. Histological analysis of ovaries confirmed the presence of actively spawning females inshore, and gonadosomatic index (GSI) values from females collected inshore (mean=7.8) were higher than the values from females caught offshore (mean=5.6); both of these mean values indicate that spawning occurred locally. Additionally, we conducted an ichthyoplankton survey in 2008 and found cobia eggs and larvae as far as 10 and 15 km inshore from the mouths of SHS and PRS, respectively. A study of egg development that we conducted in 2007 and 2008 using hatchery-reared cobia eggs provided descriptions of embryological development of cobia. Comparison of visual and quantitative characteristics of the field-collected eggs with those of the hatchery-reared eggs allowed positive identification of eggs collected in plankton samples. The ages of field-collected eggs and presence of females with hydrated oocytes in PRS and SHS observed in our ichthyoplankton survey and histological analysis indicated that wild cobia spawn in the afternoon and early evening. The inshore migration of cobia from April to June, the presence of actively spawning females, significantly higher GSI values, and the collection of eggs inside PRS and SHS all confirm that these estuaries provide spawning habitat for cobia. Because of the potential for heavy exploitation by recreational anglers as cobia move inshore to spawn in South Carolina, current management strategies may require review.
Resumo:
We monitored the movements of 45 adult Summer Flounder (Paralichthys dentatus) between June 2007 and July 2008 through the use of passive acoustic telemetry to elucidate migratory and within-estuary behaviors in a lagoon system of the southern mid-Atlantic Bight. Between 8 June and 10 October 2007, fish resided primarily in the deeper (>3 m) regions of the system and exhibited low levels of large-scale (100s of meters) activity. Mean residence time within this estuarine lagoon system was conservatively estimated to be 130 days (range: 18–223 days), which is 1.5 times longer than the residence time previously reported for Summer Flounder in a similar estuarine habitat ~250 km to the north. The majority of fish remained within the lagoon system until mid-October, although some fish dispersed earlier and some of them appeared to disperse temporarily (i.e., exited the system for at least 14 consecutive days before returning). Larger fish were more likely to disperse before mid-October than smaller fish and may have moved to other estuaries or the inner continental shelf. Fish that dispersed after mid-October were more likely to return to the lagoon system the following spring than were fish that dispersed before mid-October. In 2008, fish returned to the system between 7 February and 7 April. Dispersals and returns most closely followed seasonal changes in mean water temperature, but photoperiod and other factors also may have played a role in large-scale movements of Summer Flounder.