Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater and fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root brak. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.
Carmarthen Bay is an inlet of the South Wales coast, including notable beaches such as Pendine Sands and Cefn Sidan sands. Carmarthen Bay is partially within the Pembrokeshire Coast National Park. The Joint Nature Conservation Committee list Carmarthen Bay and Estuaries as a Special Area of Conservation.
The American shad is a species of anadromous clupeid fish naturally distributed on the North American coast of the North Atlantic, from Newfoundland to Florida, and as an introduced species on the North Pacific coast. The American shad is not closely related to the other North American shads. Rather, it seems to form a lineage that diverged from a common ancestor of the European taxa before these diversified.
Alosa is a genus of fish, the river herrings, in the family Alosidae. Along with other genera in the subfamily Alosinae, they are generally known as shads. They are distinct from other herrings by having a deeper body and spawning in rivers. Several species can be found on both sides of the Atlantic Ocean and the Mediterranean Sea. Also, several taxa occur in the brackish-water Caspian Sea and the Black Sea basin. Many are found in fresh water during spawning and some are only found in landlocked fresh water.
The beluga, also known as the beluga sturgeon or great sturgeon, is a species of anadromous fish in the sturgeon family (Acipenseridae) of the order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and formerly in the Adriatic Sea. Based on maximum size, it is the third-most-massive living species of bony fish. Heavily fished for the female's valuable roe, known as beluga caviar, wild populations have been greatly reduced by overfishing and poaching, leading IUCN to classify the species as critically endangered.
Great Bay is located in southern New Jersey's Atlantic Coastal Plain in Ocean and Atlantic Counties, about ten miles (16 km) north of Atlantic City and is about 5.5 miles northwest of Brigantine, and 5.5 miles southwest of Beach Haven. The Mullica River flows into the bay, and together they form the Mullica River - Great Bay estuary habitat. The bay is connected to the Atlantic Ocean via the Little Egg Inlet. Great Bay is considered one of the least-disturbed marine wetlands habitats in the northeastern United States.
The Rachel Carson National Wildlife Refuge is a 9,125-acre (37 km2) National Wildlife Refuge made up of several parcels of land along 50 miles (80 km) of Maine's southern coast. Created in 1966, it is named for environmentalist and author Rachel Carson, whose book Silent Spring raised public awareness of the effects of DDT on migratory songbirds, and of other environmental issues.
The skipjack herring is a North American, migratory, fresh- and brackish water fish species in the herring family Alosidae. The name skipjack shad comes from the fact that it is commonly seen leaping out of the water while feeding. Other common names include blue herring, golden shad, river shad, Tennessee tarpon, and McKinley shad. The skipjack shad is restricted to the Gulf of Mexico drainage basins. Skipjack are found in clear to moderately turbid water in areas with flow. Because they are a migratory species, dams often impede their reproduction. Records suggest that this species was much more abundant in the Upper Mississippi River basin before it was impounded. Currently, skipjack is most abundant in the Upper Mississippi River below the mouth of the Ohio River. They are known as an "early-run" species as they migrate to spawn in the early spring.
The hickory shad, fall herring, mattowacca, freshwater taylor or bonejack is a member of the family Alosidae, ranging along the East Coast of the United States from Florida to the Gulf of Maine. It is an anadromous fish species, meaning that it spawns in freshwater portions of rivers, but spends most of its life at sea. It is subject to fishing, both historic and current, but it is often confused with or simply grouped together with American shad in catch statistics.
The allis shad is a widespread Northeast Atlantic species of fish in the Alosidae family. It is an anadromous fish which migrates into fresh water to spawn. It is found in the eastern Atlantic Ocean, the western Baltic Sea and the western Mediterranean Sea. In appearance it resembles an Atlantic herring but has a distinctive dark spot behind the gill cover and sometimes a row of up to six spots behind this. It sometimes hybridises with the twait shad. This fish becomes mature when three or more years old and migrates to estuaries, later swimming up rivers to spawn. Populations of this fish have declined due to overfishing, pollution and habitat destruction. Conservation of this species is covered by Appendix III of the Bern Convention and Appendix II and V of the European Community Habitats Directive.
Shad is a type of fish, much valued as a sport fish. The male shad is an excellent game fish, showing multiple jumps and an occasional end-over-end; it has been called a "freshwater tarpon". The gravid female does not fight much, but is often kept for the roe. The current world record is listed by the IGFA as 11 pounds 4 ounces (5.1 kg), set at Holyoke Dam, Massachusetts, on 19 May 1986 by Robert A. Thibodo.
The blueback herring, blueback shad, or summer shad is an anadromous species of herring from the east coast of North America, with a range from Nova Scotia to Florida. Blueback herring form schools and are believed to migrate offshore to overwinter near the bottom.
The Pontic shad, also referred to as the Black Sea shad or Kerch shad, is a species of clupeid fish in the genus Alosa, native to the Black Sea and Sea of Azov basins.
Alosa kessleri, also referred to as the Caspian anadromous shad, the blackback, or the black-spined herring, is a species of alosid fish. It is one of the several species of shad endemic to the Caspian Sea basin.
The Killarney shad, also called the goureen, is a freshwater fish in the family Alosidae, endemic to a single lake in Ireland, Lough Leane in County Kerry. Research has shown that it is a landlocked subspecies of the anadromous, twait shad, arriving in the lake after the Last Glacial Maximum about 10,000 years ago. This fish is at risk from eutrophication and the introduction of alien species of fish to the lake and the International Union for Conservation of Nature has rated it as "critically endangered".
The Shad Foundation is an international non-profit 501(c)(3) organization established in 1996 for the study, protection, and celebration of shads around the world. Currently, there are more than 30 recognized shad species worldwide. Shad, which are members of the herring family, are widely distributed, and many are anadromous, meaning that they migrate from fresh to salt water as juveniles and return to freshwater for the express purpose of spawning. Many species are threatened by water pollution, overfishing, habitat destruction, and obstacles to migration, such as dams.
The Alabama shad is an anadromous species of alosid fish endemic to the United States where it breeds in medium to large flowing rivers from the Mississippi River drainage to the Suwannee River, Florida, as well as some other Gulf coast drainages. The biology of this fish is little known but it has become increasingly rare. The International Union for Conservation of Nature rated it "near threatened" in 2020 and the United States National Marine Fisheries Service has listed it as a Species of Concern. A principal reason for its decline is thought to be the many locks and dams blocking access for the fish to up-river spawning grounds.
Aber Taf is a large Site of Special Scientific Interest (SSSI) in Carmarthenshire, Wales, and forms part of the Carmarthen Bay and Estuaries Special Area of Conservation.
