The anal fin is found on the ventral side of fish, often, but not always, at the base of the anus. Along with the dorsal fin, the main purpose of the anal fin is stabilize the fish and keep it from rolling in the water. For knifefish (order Gymnotiformes), which have neither pelvic or dorsal fins, … [Read more…]
The pelvic fins are paired fins found on the ventral (bottom) side of fish. In teleost (bony) fishes, pelvic fins placement gives some indication of evolution. For more basal groups, the pelvic fins are located at mid-body in the abdominal region. For more derived fishes, the pelvic fins are located in a thoracic or even … [Read more…]
The pectoral fins are the two fins located on the sides of a fish (or marine mammal). These fins are primarily responsible for control of directional movement, up and down or side to side. Pectoral fins can come in all shapes and sizes which fill different functions for different fish. The pectoral fins of a … [Read more…]
The dorsal fin is located on the top of a fish (as well as some marine mammals). Predominately, the fin is used to stabilize fish in the water and help direct the fish through turns and stops. Some fish, like Striped Bass (Morone saxatilis), have two dorsal fins and others have very highly derived dorsal … [Read more…]
The caudal fin, or tail, of a fish is the only fin to be connected to the vertebral column. It is the primary means of locomotion for most fish. Unlike many marine mammals with tails that use an up-and-down motion, fish generally use a side-to-side thrust of their caudal fin for propulsion. The shape of the … [Read more…]
The adipose fin is a small fleshy fin found posterior to the dorsal fin and anterior of the caudal fin. It is only found on few fish, including trout, salmon, and catfish. When it was named, it was thought to hold fat, or adipose, tissue. Once this hypothesis was disproved, fisheries biologists long considered this … [Read more…]
The pelagic zone is the region of a body of water (lake, river, or ocean) that is not associated with the bottom (see benthic zone) or shore (see littoral zone). This habitat zone is truly a three dimensional habitat space. Some fish that occupy the pelagic zone never encounter the bottom or shore throughout their … [Read more…]
The benthic zone is region of a body of water (lake, river, or ocean) that is near the bottom. It includes the surface and some of the sub-surface layers of the sediment. The sediment can sand, mud, rocks, coral, among other substances. Benthos are organisms living in the benthic zone. These organisms are predominately invertebrates, … [Read more…]
The littoral zone is the region of a body of water (lake, river, or ocean) that is near the shore. While there is no exact definition of the zone, in marine systems it is generally considered to extend from the high-water mark to the continental shelf; freshwater systems it is generally considered to be wetland … [Read more…]
IUU fishing is illegal, unregulated, and unreported fishing. According to the 2001 FAO International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported, and Unregulated Fishing, Illegal fishing refers to activities: conducted by national or foreign vessels in waters under the jurisdiction of a State, without the permission of that State, or in contravention … [Read more…]