Notes On Depleting Fish Stock

Ruth Francis-Floyd, professor, Department of Large Animal Clinical Sciences (College of Veterinary Medicine) and Department of Fisheries and Aquatic Sciences, UF/IFAS Extension, Gainesville, FL 32611.

Boats are very common on the lake, both for fishing and recreation. The lake is a popular to anglers looking for kokanee salmon (Oncorhynchus nerka) and lake trout (Salvelinus namaycush). Other fish like rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) are also abundant in the lake. Mysis shrimp were introduced into the lake many years ago. They have had an impact on the kokanee salmon and will be analyzed in the final paper. The fishing industry provides income for the area, as well as jobs. As of recent, the populations of kokanee salmon and lake trout have been in a decline. The interaction of human management on these fish populations is needed in order to help increase these fish abundance in the lake. This issue is also linked to the management of water in the lake because water levels impact the way that fish species

The Atlantic cod fishery collapse left terrible ecological consequences. As mentioned above, the fishing technology was a major destruction to the ecological system by using deployment and draggers. The huge nets that were dropped and dragged along the bottom of the ocean destroyed the underlying eco-system in the process. The effect of selective fishing on spawning grounds – that is, selectively over-exploiting one species in an ecosystem – had disastrous effect on the feeding relationships in that ecosystem. This contributes to the overall reduction of spawning stock biomass of the targeted species, but also an increase in the number of invertebrate and vertebrate predators such as crustacean and fish which will prey on cod eggs, larvae, and younger fish. It is a little wonder that a species like cod, would eventually run into difficulties struggling to survive when its habitat is being continuously destroyed and the balance of their food chain had been wiped out.

Salinity tolerance of yolk-sac larvae and swim-up fry of channel catfish (Ictalurus punctatus), blue catfish (I. furcatus), and channel catfish, I. punctatus, ♀ × blue catfish, I. furcatus, ♂ hybrid catfish was investigated at 0, 3, 6, and 9 ppt salinity. No yolk-sac larvae or swim-up fry survived for channel catfish, blue catfish, and hybrid catfish at 9 ppt for either stage of development, and no mortality was observed at 0 ppt for yolk-sac larvae for all genetic groups. Survival among the genetic groups was different (P < 0.05) by day 3 and day 4 post-hatch at 3 ppt, (P < 0.05) with blue catfish > hybrid catfish > channel catfish for salinity tolerance. At 6 ppt blue catfish had the highest survival for yolk-sac fry through day 2, but by day 3 blue catfish had the lowest tolerance and channel catfish the highest.

This paper observes the efficiencies of three different feed types fed to Epinephelus coioides. These feed types include a soy-based plant protein pellet (AQUA-LIFE), fish meal pellets (Ridley Aqua Feeds) and whole Pilchards. The fish had their dry weight and length measured prior to the commencement of the trial. 12 tanks, with 5 fish per tank were fed the three different feed types. All fish were fed every day of the 5 week trial period. The results showed the fish meal pellets had the most efficient food conversion ratio (FCR) value (0.84), with a standard growth rate (SGR) of 4.28 grams per week. This FCR value was substantially more efficient compared to the value of 2.20 and 2.98 for the Pilchards and plant based protein respectively. Several mortalities occurred in the fish being fed plant based protein, possibly due to high aggression as a result of a lack of nutrients. Water quality parameters were also not ideal for the growth of the fish as all nitrogen levels were above the ideal threshold, with nitrate reaching 89 ppm before a water change was conducted. In conclusion, the fish meal pellets proved to be the most

There is increasing evidence in numerous scientific studies that show that widespread marine species can be highly structured genetically and may speciate very quickly. Genetic differentiation of populations in the Indian and the Pacific Oceans has been reported for coconut crabs (Lavery et al. 1996), the starfish Linckia laevigata (Williams and Benzie 1997), butterfly fish (McMillan and Palumbi 1995), damsel fish (Lacson and Clark 1995), and the mangrove Avicennia marina (Duke et al. 1998). Despite the evidence of high gene flow within the Indian and the Pacific Oceans, this still holds true. This suggests that there is high dispersal over large areas. However, there is limited dispersal between zones.

According to a study done by Living Planet Report in 2015, 29% of the world’s fishing stocks are considered overfished and an additional 61% is fully exploited with no possibility to produce more fish. Our environment is currently afflicted by a number of different problems, one of which is overfishing. Overfishing is defined by FishOnline as, “Fishing with a sufficiently high intensity to reduce the breeding stock levels to such an extent that they will no longer support a sufficient quantity of fish for sport or commercial harvest.” The overfishing situation is being exacerbated by non-sustainable and destructive fishing practices and unfair fisheries partnership agreements; while there are currently attempts being made at fixing these problems and their effects on overfishing, nothing has been extremely effective.

The south pacific is well known for their upwelling especially around the coast of Peru and it is well known for its high productivity around the world’s oceans and supports a great deal of sea food around the world. However, the region is also known for its fluctuation in the fish stocks due to many biotic and abiotic factors (Figure 1) (Cury, Roy, and Faure 1998; Sandweiss et al. 2004).

This issue of overfishing covers vast fields, such as science, humanity, economy, society and nature. The term “optimum”, in regard to the yield from a fishery, is difficult to be defined, precisely and fixedly. Generally speaking, we can describe it as follows: (Niles E. Stople, January 2009, FishNet USA)

Shellfish diversity was found dominated all the years with a maximum of 72% during 2011-12 which was followed by finfish diversity with 58% occurrence in the year 2013-14. There is an increase in the shellfish biodiversity up to 2011-12 from then a sudden decrease of shellfish was observed (32%) and a further decrease of shellfish occurrence was found in 2013-14. The major shellfish biodiversity of cage site during the present study was recorded as fouling on cage frames, nets and barrels.

Due to the importance of fishing to the worldwide economy and the need for humans to understand human impacts on the environment, the academic division of fisheries science was developed. Fisheries science includes all aspects of marine biology, in addition to economics and management skills and information. Marine conservation issues like overfishing, sustainable fisheries and management of fisheries are also examined through fisheries science.

According to the United Nations, 17% of fish stocks worldwide are currently overexploited; 52% are fully exploited; and 7% are depleted. This means that only an estimated 20% of worldwide fish stocks are not already at or above their capacity(Seafarms, 2013). Catches of Pacific herring have decreased by 71% since the 1960s, with Atlantic herring catches falling by 63%. Atlantic Cod catches have fallen by 69% in the same time(Seafarms, 2013). These are just a few of many facts and statistics on the topic of overfishing. The effects of these statistics and facts impact people’s and animal's lives around the

In today’s global economy sustainability is very important; from the biological aspect to the industries they all play a role on the marine environment. As world population increases the demand of fish rises causing overfishing. Certain laws have been placed to limit the amount of wild fishing to reduce the risk of endangerment. To meet the demand of the population, fish farms are introduced. Pollution and health related issues are part of the challenges of fish farming. Sustainability also affects social areas such as beaches.

Overfishing has become a devastating reality and priority concern to our Oceans in South Africa, as well on a global scale. The interest of overfishing, is to eradicate hunger issues in developing countries all over the world, as well as to create a vast improvement of job opportunities, however due to our unsustainable fishing practices, it is just a matter of time before our oceans are completely depleted of marine species, and the destruction of the aquatic ecosystem. This issue will resort to irreparable socio-economic and environmental circumstances that will be of severe consequence if we do not alter our local and international commercial fishing operations. Due to overfishing throughout the continents, South African waters has become a viable target for international role players to maintain the demand of fishing operations and fish stocks that is required for global markets. Due to inadequately monitored fishing operations, overfishing has left South Africa with a significant shortage of food resources for the poor, who depend on fish as their staple diet. According to the World Wildlife Fund, “Seafood is the largest traded food commodity in the world. Approximately three billion people worldwide rely on seafood as their primary source of protein. As the world tries to meet that demand, 55 percent of the world’s fisheries are fished to their maximum sustainable yield, while 30 percent have been pushed beyond their biological limits. Preserving healthy fish

In the systematic of the fishes of India considerable advanced have been made since the publication of the fishes of India by Day [1878], and his two volume of fishes in Fauna of British India Series [1889], Mishra 1947 made valuable contribution in the preparation of the series of the check list and aids of the fishes of India, Burma, and Ceylon is commendable. Further more Menon [1949] studies the fish collection of India Museum reported several new forms. ]Tremendous work has been done in North India by a number of workers. Menon [1962] studies the fishes of Kumaon Himalaya, Choudhary and Khandelwal [1966] observed the fishes of Nainital. There works have added valuable information’s regarding the bionomics, distribution and morphological description of new forms