shell fishery and classification of shell fisheries.

Shell Fishery

Shellfishery is the industry and commerce of catching, processing, and selling shellfish for profit.

Shell Fish

Shellfish differ from finfish in that they have hard outer shells and no backbones or internal skeletons.

Classifications

• Shellfish can be divided into three groups:
• THE CRUSTACEANS:
•  have segmented bodies and firm shells • EX: shrimp, lobster, crabs
•  MOLLUSKIES Oysters, clams, scallops, and other cephalopods have soft bodies that are partially covered by hard shells.

•  Have a reduced internal shell known as a cuttlebone; for example, octopus and cuttlefish.

1. Crustaceans

Have a hard outer skeleton or shell - Appendages with joints - Bone, outer jointed shell.

• Crustacean, any member of the subphylum Crustacea (phylum Arthropoda), a group of 45,000 species of invertebrates found worldwide. Crabs, lobsters, shrimps, and wood lice are among the most well-known crustaceans, but the group also includes a vast array of other forms with no well-known names. Crustaceans are typically aquatic, with two pairs of appendages (antennules and antennae) in front of the mouth and paired appendages near the mouth that function as jaws. However, because there are numerous exceptions to the basic characteristics, a satisfactory inclusive definition of all Crustacea is exceedingly difficult to formulate.
• Important for Humans

The larger crustaceans, particularly decapods, are the most obvious to humans. Fisheries in many parts of the world capture shrimp, prawns, spiny lobsters, and the northern Pacific king crab (Paralithodes) and its southern counterpart, the centolla, found off the coast of Chile. Many true crab species, including the blue crab, Dungeness crab, and stone crab of North America, as well as the edible crab of Europe, are valuable sources of food. The most valuable decapod is probably the true lobster (Homarus species), though overfishing has greatly reduced catches of both the North American and European species since the early twentieth century. Crayfish, river prawns, and river crabs are examples of freshwater crustaceans. Many species only have a local market value. It is unlikely that any crustaceans are poisonous unless they have eaten poisonous plant leaves or fruits.

2) Cray fish

Small freshwater fish ranging in size from 2 to 8 inches.

crayfish, also known as crawfish or crawdad, any of a variety of crustaceans (order Decapoda, phylum Arthropoda) that comprise the families Astacidae (Northern Hemisphere), Parastacidae, and Austroastracidae (Southern Hemisphere). They are relatives of the lobster. North America is home to more than half of the more than 500 species. Although a few species live in brackish or salt water, the vast majority live in fresh water.

Crayfish have a joined head and thorax, or midsection, as well as a segmented body that is sandy yellow, green, red, or dark brown in colour. The head has a pointed snout and compound eyes on movable stalks. The exoskeleton, also known as the body covering, is thin but tough. The pincers on the front pair of the five pairs of legs are large and powerful (chelae). The abdomen has five pairs of smaller appendages that are mostly used for swimming and circulating water for respiration.

The average adult crayfish is about 7.5 cm (3 inches) long. The 2.5-cm-long Cambarellus diminutus of the southeastern United States is one of the tiniest. Astacopsis gouldi of Tasmania is one of the largest, reaching 40 cm in length and weighing about 3.5 kg (8 pounds).

3. Crabs

Any short-tailed member of the crustacean order Decapoda (phylum Arthropoda) is referred to as a crab. This includes true crabs, such as the brachyurans (infraorder Brachyura), as well as various varieties such the anomurans (suborder Anomura), which includes hermit crabs. All oceans, freshwater, and land are home to decapods; over 10,000 different species have been identified.

Crabs' tails are curled under the thorax, or midsection, unlike those of other decapods (such as shrimp, lobster, and crayfish). Typically, the carapace (top body shield) is wide. The first pair of legs are transformed into pincer-like chelae.

Types

Stone crabs,

 King crabs, 

Dungeness crabs,

 blue crabs,

 snow or spider crabs,

stone crab

king crab

Blue crab

Dungeness crabs,

snow or spider crabs,

4.Lobsters

lobster, any of the numerous marine crustaceans that belong to the families Homaridae (or Nephropsidae), real lobsters, Palinuridae, spiny lobsters or sea crayfish, Scyllaridae, slipper, Spanish, or shovel lobsters, and Polychelidae, deep-sea lobsters (phylum Arthropoda, order Decapoda). They are all benthic (bottom-dwelling) and marine, and the majority are nocturnal. In addition to eating living fish, small mollusks, and other invertebrates that live on the ocean floor, lobsters also scavenge for dead animals. Some species, particularly true and spiny lobsters, are valuable to humans commercially as food.

The lobster has five pairs of legs, one or more of which are frequently converted into pincers (chelae), with the chela on one side typically larger than the chela on the other. It also has a stiff, segmented body covering (exoskeleton). The enormous abdomen of a lobster is covered in multiple pairs of swimming legs (swimmerets), two pairs of long antennae, and compound eyes on movable stalks. The animal swims with a muscular tail that resembles a flipper, and it moves backward by flexing its tail and abdomen.

Types

• Maine lobsters
•   Spiny lobsters
•   Slipper lobsters
•  Langoustine

5.Shrimps

Although certain crustaceans outside of the decapod order are referred to as "shrimp," shrimp are actually crustaceans with elongated bodies and a primary form of locomotion that involves swimming. The most common species of shrimp are Caridea and Dendrobranchiata.

Shrimp have lengthy, muscular abdomens and are slim. They resemble little lobsters in certain ways, but not crabs. Crabs have small, short abdomens, but lobsters and shrimp have big, lengthy abdomens. Shrimps have pleopods in their lower abdomens that are well-suited for swimming. Crabs have broad, flat carapaces, whereas lobsters and shrimp have more cylinder-shaped carapaces. Crabs have short antennae, whereas the antennae of lobsters and shrimp are typically lengthy and can extend to more than double the length of the body in some shrimp species.  

Shrimp are widely available and plentiful. There are countless animals that have evolved to a variety of settings. On most coasts and in most estuaries, as well as in rivers and lakes, they can be seen feeding close to the seafloor. Some animals flip off the seafloor and dive into the silt to avoid predators. Usually, they have a lifespan of one to seven years. Despite the fact that shrimp frequently live alone, they can form vast schools during the breeding season.

6.Prawn

A small aquatic crustacean with ten legs and an exoskeleton known as a prawn belongs to the decapoda order and is sometimes consumed.

In the United Kingdom, Ireland, and other Commonwealth countries, large swimming crustaceans or shrimp, particularly those with commercial significance in the fishing sector, are referred to as "prawns." The shrimp found in this group frequently come from the suborder Dendrobranchiata. The phrase is less frequently used in North America, typically for freshwater shrimp. Even the phrases "shrimp" and "prawn" are not considered scientific. The phrases have evolved over time, and in modern usage, they are essentially interchangeable.

an enormous river shrimp. However, this enormous, freshwater species is a caridean shrimp and is only occasionally referred to as a prawn. Prawns are occasionally described as large shrimp or, alternately, freshwater shrimp.

7.Mollusks

Soft aquatic creatures are mollusks. Two are present that are mostly eaten

The most cherished member of the mollusk family, the oyster, has two hinged shells. Types that are frequently eaten: clams, oysters, mussels, and scallops. Taste depends less on species and more on where they are farmed.

The soft-bodied invertebrate group known as mollusks typically has a soft mantle covering its body and is entirely or partially contained in a calcium carbonate shell. With about 100,000 (perhaps as many as 150,000) known species, mollusks are one of the most varied groups in the animal kingdom, along with insects and vertebrates. This is a list of noteworthy mollusks, arranged by class and alphabetically. Extinct mollusks are also featured.

Univalves have a single shell (like conch, abalone) 

 Snails the best known of univalves

8.Octopus

Any eight-armed cephalopod (octopod) mollusk belonging to the order Octopoda is referred to as an octopus, plural octopuses or octopi. Members of the genus Octopus, a sizable collection of widely dispersed shallow-water cephalopods, are the real octopuses.

The smallest species of octopus, O. arborescens, is only around 5 cm (2 inches) long, while the largest species can reach lengths of up to 5.4 metres (18 feet) with an arm spread of approximately 9 meters. The typical octopus has a saccular body with eight contractile arms and enormous, complex eyes that are barely distinguished from the body. Two rows of fleshy suckers with strong holding capacity are present on each arm. A web of tissue known as the skirt, with the mouth at its center, connects the bases of the arms to one another. The latter organ has two pointed, horny beaks and a radula-like organ for rasping and drilling shells.

9.Cephalopods

Cephalopods are a tiny group of highly developed and organized, only marine animal species. They belong to the class Cephalopoda of the phylum Mollusca. The familiar representatives include the octopus, squid, cuttlefish, and chambered nautilus. The class reached tremendous variety in the late Paleozoic and Mesozoic periods, when the extinct forms outnumbered the live ones. Except for the five species of Nautilus that are still alive, the extinct cephalopods include ammonites, belemnites, and nautiloids.

 The cephalopods share a fundamental structure with the remainder of the Mollusca, and their forebears seem to have the closest kinship with those of the class Gastropoda. The cephalopods' most recognisable characteristic is their arm and tentacle count, which ranges from eight to ten in the majority of forms to roughly 90 in the Nautilus. With the exception of the nautilus, every living member of the class exhibits significant reduction and alteration of the distinctive molluscan shell.

The size of cephalopods varies widely. The largest extant invertebrates are giant squids (Architeuthis species); A. dux can grow to a length of more than 20 metres (60 feet), including the extended tentacles. The squid Idiosepius, which is rarely longer than an inch, is the tiniest cephalopod. The typical octopus's limbs are rarely longer than a metre and rarely more than 30 centimetres (12 inches). However, Octopus dofleini has been known to have arms as long as nine metres (30 feet). The largest shelled mollusk is thought to have been the fossilised ammonite Pachydiscus seppenradensis, whose shell measured 205 centimetres (6 feet 8 inches) in diameter.

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