User:Bbrake12/sandbox

Tuna Farming

Introduction

Tuna has been a major conservation concern in recent years due to its high demand in the seafood market. Tuna are some of the highest commercially valued fish in the world and therefore are sought after from fishermen all around the world. Countries of main concern include Japan and Spain. Various species of tuna are currently in a major decline, with some on the brink of extinction. Therefore, the IUCN (International Union for Conservation of Nature) has listed each fish in a different category according to its value. The major species that will be discussed on this page are the Atlantic Bluefin tuna (Thunnus thynnus), southern bluefin tuna (Thunnus maccoyii), and yellowfin tuna (Thunnus albacares). Conservation biology is extremely important to the future of these species. Fisheries and aquaculture practices can substantially influence tuna for years to come. The International Commission for the Conservation of Atlantic Tunas (ICCAT) is the responsible body which must take actions soon to conserve this valuable fish.

Background

Species of major concern include the Atlantic bluefin (endangered), southern bluefin (critically endangered), and yellowfin tuna (near threatened). These three species range in size. Yellowfin tuna can grow up to about 440 pounds; Atlantic bluefin tuna can grow up to 1,510 pounds. Tuna are some of the fastest species in the deep ocean and can swim up to 47 mph. Finlets on the top and bottom along with a defined keel located towards their tail provide them with the ability to outswim just about any species in pelagic waters. Each of these fishes roams oceans and seas from the Pacific to the Atlantic mainly along the equator. Spawning grounds include smaller seas such as the Gulf of Mexico and Mediterranean which provide calmer and more protected waters for younger tuna. Depending on where tuna are located, they usually feed on various types of small fishes and squid.

Reasons for decline

The market for tuna is the highest of all fishes found in the deep oceans. Prices of tuna range from $9 per pound up to about $1,200 per pound depending on the market at the time the fish is harvested and sold. Tuna can be sold as a canned food, but is especially well-known for its value as sushi. Sushi started as a cultural dish in Japan; however it has now become a global phenomenon. Due to the high demand for tuna meat, fishermen in countries all around the world have found various ways to harvest these fishes. One of the earlier methods of tuna fishing included purse seining, which consists of a vessel dragging a large net from behind the boat that has weights along the bottom and corks on the top to catch all tuna caught in between. In addition, another popular method fishermen invented is long-lining ocean waters. This method consists of an anchored line with baited hooks attached to the main line which can hook tuna in any depth of the oceanic zones. Despite the effectiveness of both methods, each can negatively impact other oceanic species such as sea turtles, billfish, and various other undesired species. Each of these methods is performed at a commercial scale and is among the major reasons for declines in population sizes. Furthermore, tuna fishing can be performed at a lower scale as well. Fishermen can acquire licenses which allow them to charter recreational fishermen out into waters to catch various species of tuna on rod and reel, making it a much sportier method. Although tuna provide jobs for people around the world, rules and regulations must be implemented in order to preserve these vulnerable fish.

Recovery plans (tuna farming)

Tuna farming research has increased in recent years due to the decline of such a sought after species. Both deep ocean operations and even land operations have been developed as major recovery plans. By catching wild tuna with nets and placing them into large pens both onshore and offshore, researchers can control tuna and provide possible reproduction in captivity.

Deep ocean operations include the farming and fattening of tuna in oceanic waters. Wild tuna are caught in the wild then placed into pens up to 200 feet deep for farming in captivity. Once placed into these pens, tuna are fed various species of small fishes which are rich in fat and low-cost. Keeping fish in their natural habitat allows them to spawn naturally. Therefore, scuba divers search the pens to monitor reproduction during the spawning season (June to July). In one case study, reproduction was first accomplished in Japan with bluefin tuna. In June of 2002, wild breeders produced 1 million eggs for the first time. Furthermore, another operation in Italy produced spawning of over 20 million eggs over four consecutive days. These eggs were transported to a commercial hatchery and resulted in the first ever production of aquacultured Atlantic bluefin tuna fry. This closure of production was a big jump towards the future of a full-scale aquaculture plan for this vulnerable species.

A much more recent operation that is being considered in some countries is the use of land operations. In land-based facilities, researchers can farm tuna while mimicking offshore habitats to create spawning opportunities in a much more controllable environment that can prevent mortality from stress and cannibalism. A small country located in the Mediterranean Sea made a huge breakthrough by successfully hatching tuna larvae in a land-based facility. This operation mimics oceanic light and water temperatures that produce ideal survival conditions for young tuna fry. In 2011, scientists at the facility kept larvae alive for more than 70 days. Now they see a possibility of growing bluefin tuna up to a kilo, which is a big jump from the previous year’s success.

Recovery plans (management options)

Some management actions that can be taken into action include ICCAT lowering quotas for commercial fishermen. In 2010, ICCAT reduced total allowable catches for fishermen from 32,000 tons to 13,500 tons. In addition, shortening catch season would help decrease the amount of tuna being harvested each year. International trade of tuna fishes has created a problem for ICCAT. It is hard for this intergovernmental organization to monitor each trading station around the world efficiently. Consequently, banning international trade would prevent illegal trade in the black market and create much easier regulation of how much tuna each seafood market is receiving and pushing out.

Goals

Some of the main goals conservationists are targeting are bringing tuna back to sustainable population growth rates, if not increasing population growth rates. Also, promoting more deep sea tuna farming as well as more successful land-based facility operations could play a huge role in the conservation of this vulnerable species. The development of a true self-sustained aquaculture industry of tuna will help relieve some of the pressure on the wild fisheries and in return aid in the conservation of this valuable fish.