Sea Fishing Environmental Effects Over

¶ … Sea Fishing

Environmental Effects Over fishing Deep Sea Fisheries

The environmental impacts of deep sea over fishing are many, including detrimental reductions in fishing species/populations. Over fishing can result in a modified community species composition and reduced genetic diversity through "selective targeting on species and particular size classes" (Shotton, 2003).

Over fishing has the greatest impact on the environment at large. Reductions in genetic diversity and in species or populations alter the composition of habitats and can impact the environment in many ways. Coral reefs are one example, facing extinction because of a lack of herbivorous species to keep algae in check.

The equipment utilized by deep sea fisheries may also impact the environment in a negative way. Not only are habitats and ecosystems destroyed as a result of deep sea fishing, but entire species are on the verge of distinction, while other non-target species have also been impacted in a negative manner. The research below will describe the environmental impacts of deep sea fishing in greater detail.

Consequences of Over fishing on Environment

By far the most obvious impact of over fishing is the devastation of ecosystems and marine life communities (Simpson, 2001; Dayton, Thrush, Agardy, & Hofman, 1995). Over fishing may impact other species directly by simply killing available populations, or indirectly, via increased "incidental mortality" that occurs as a result of lost or abandoned gear, and destruction of the existing sea bed due to the equipment used by fisheries including trawls, dredges, dynamite and abandoned gear (Shotton, 2003). At any time that a species is drastically reduced the ecosystem and subsequent environment as a whole is affected in a negative manner.

Over fishing also has many indirect effects on marine ecosystems including pollution, noise and air travel pollution and habitat destruction (Shotton, 2003). All of these effects can also affect an economy, which must work to restore the ecosystems most affected by over fishing, and work to find new ways to supplement the populations that have been dying off.

Destructive fishing practices are common in environments that have been over fished. Bottom trawls are an example of how over fishing can destroy environmental habitats. Bottom trawls are equipment used to catch "groundfish" and other crustacean species including crab and crawlers; they are considered one of the most destructive forms of equipment because they "directly threaten species richness and biodiversity" and also catch many non-target species in addition to the species for which they are intended (CSI, 2004).

Deep sea corals and sponges are among the habitats that are often destroyed by bottom trawls (CSI, 2003). Any bottom dweller will be indirectly affected by the use of heavy equipment that invades the natural habitat (CSI, 2003).

Another common way that over fishing impacts environmental destruction is via use of long line fishing, where a line up to eight miles long is set out, consisting of baited hooks. These lines catch many unintended species as well including birds and turtles. Researchers estimate that as many as 180,000 birds die as a result of these hooks each year, and that many of the birds caught on these hooks are rare or endangered species (CSI, 2003). Still other deep sea fisheries practices that have been identified as hazardous include the use of flash fishing and the use of sodium cyanide, which taints the fish it captures (CSI, 2003).

As a result of over fishing, the size of fish in the deep sea has also decreased over time (Clarke, 2003). Studies show that fish in the North Sea have gotten smaller with time and over fishing has been cited as a cause (Clarke, 2003). According to ecologists from the Netherlands Institute for Fisheries Research, fish that are smaller than 30 centimeters in length are increasing in numbers (Clarke, 2003). The idea is that over fishing of larger fish including cod and hake allows more small fish to survive. Thus the entire composition of many marine ecosystems is changing. Researchers and citizens alike have good reason to be concerned, as the long-term consequences of habitat destruction and the change of ecosystems is unpredictable and uncertain at best.

Houlder (2003) notes that coral reefs are in danger of extinction if immediate action is not taken to preserve and protect them, due primarily to over fishing and pollution. The Great Barrier Reef for example, considered the best protected reef, "is nearly a third of the way toward extinction" and in other places including Jamaica corals are all but extinct (Houlder, 2003).

Coral reefs began declining when more and more large fish, turtles and seals were killed, species which in the past had frequented coral reef systems. The "reduced visits" have led to a reduced number of herbivorous fish and "added nutrients from pollution" all of which result in seaweed overgrowth and destruction of the reef (Houlder, 2003).

Methods for Addressing Over fishing

The government has encouraged many fisheries and local agents to develop strategic plans for combating the problem of deep sea over fishing. In particular much attention has been spent on an 'ecosystem' approach to fishery management which is adaptive, geographically specified and works to balance diverse objectives (Shotton, 2003). An ecosystem approach aims at "conserving the structure and function of marine ecosystems and the fishery resource" (Shotton, 2003).

Longlines can be weighted so that bait sinks faster, and hooks can be set at night, thus reducing the impacts on unintended species including birds (CSI, 2003).

Studies suggest that over fishing is impacting deep sea fishing populations and ecosystems in many negative ways. Unless firm and well thought out actions are developed to provide fishing communities with some relief, the entire marine ecosystem as a whole may change dynamically in the next decade, with unforeseen consequences.

Some ecologists have noted that "there is no place in the ocean left where there are undisturbed fish stocks... The whole ocean has been transformed" (Harder, 2003). In order to realize improvement, governments need to work together on a global level to change the way the activities of deep sea fishing are managed. One method of improvement may depend upon the creation of protected marine areas where fishing is banned, and reduced fishing permissions in other areas where the worst impacts of over fishing is evident (Harder, 2003).

Typically the goal of a fishery is to produce a 'sustainable yield' which happens when fishing stock is kept at approximately half of its natural size (Harder, 2003). At this time, fish generally tend to grow and reproduce more rapidly than in an ecosystem that is more crowded (Harder, 2003). However for most species that are impacted by over fishing, the marine biomass is decreased beyond the halfway point, so that a sustainable yield is not possible, because fish do not have the opportunity to replenish themselves adequately (Harder, 2003).