User:Margaretbhanna/Environmental impact of fishing

Fisheries management
Much of the scientific community blames the mismanagement of fisheries for global collapses of fish populations. One method for increasing fish population numbers and reduce the severity of adverse environmental impacts and ecological disturbances is the use of fisheries management systems. Traditional fisheries management techniques can signify restricting certain types of fishing gear, reducing the total allowable catch, decreasing fishing efforts as a whole, implementing catch shares, involving communities with conservation efforts and defining areas closed to fishing. In order to implement any of these tactics on a fishery, ample data collection and statistical analysis are necessary.

Whether or not traditional fisheries management techniques are effective at restoring fish populations is often seen as a debate in the fisheries science community. However, there are a few factors to consider when evaluating the efficiency of fisheries management techniques. For example, large fisheries are more likely to be managed whereas small fisheries are commonly left unassessed and unmanaged. Unassessed fisheries are thought to represent about 80% of all fisheries. Some researchers believe that the stability and health of these unassessed fisheries are worse than the assessed fisheries, justifying the premise that traditional fisheries management techniques are ineffective. However, many scientists highlight that those fish populations are declining due to the fact that they have not been assessed and therefore adequate fisheries management techniques have not been applied. Further, most of the assessed fisheries (and hence managed fisheries) are biased towards large populations and commercially lucrative species. Assessments are often performed by nations that are able to afford the assessment process and implementation of fisheries management tools.

Determining sustainable harvest quotas are another example of a traditional fisheries management technique. However, the intention behind harvest quotas are often not a big enough incentive for fishermen to adhere to them. This is because limiting individual harvests often leads to a smaller profit for the fleet. Since these fishermen are not guaranteed compensation for part of the quota, they tend to resolve to the method of harvesting as many fish as possible. This competitiveness among fishermen and their fleets leads to the increased use of harmful fishing practices, extremely large harvests, periods of reduced stocks and the eventual collapse of the fishery. To eliminate the need for such competitiveness among fishermen, many scientists suggest the implementation of rights-based fisheries reforms. This can be done by granting Individual Transferable Quotas (ITQs) or catch shares, a set portion of a scientifically calculated total allowable catch, to individual fishermen, communities and cooperatives. ITQs incentivize fishermen because the value of catch shares grows as the stability of the fishery improves.

It is estimated that around 27% of global fisheries were classified as collapsed in 2003 and that by 2048, 100% of global fisheries would be considered collapsed. In a study compiling data from 11,135 fisheries around the world (some ITQ-managed, some non-ITQ managed), the potential impact of ITQs on fisheries if they all implemented a rights-based management approach since 1970 was estimated. In that case, the percentage of collapsed fisheries in 2003 was projected as 9%, which remained fairly stable for the rest of the experiment's time period. Despite the projected success of the ITQ-managed fisheries, the results of this study may not be a completely accurate representation of the true impact of right-based management. This is due to the fact that the data used to create these results was limited to one type of catch share and that the true effects of ITQs can only be assessed if social, ecological and economic factors were also considered.

In some cases, changing fishing gear can have an impact on habitat destruction. In an experiment with three different types of gears used for oyster harvesting, compared to dredging and tonging, hand-harvesting by divers resulted in the collection of 25-32% more oysters within the same amount of time. In terms of habitat conservation, the reef habitat sustained damage to its height during the use of all three gear types. Specifically, dredging cut the height of the reef by 34%, tonging by 23% and diver hand-harvesting by 6%.

Opting for a different hook design or bait type can make fishing practices less dangerous and leads to less bycatch. Using 18/0 circle hooks and mackerel for bait has been shown to greatly reduce the amount of leatherback sea turtles and loggerheads caught as bycatch. The use of circle hooks was shown to decrease the amount of hooks ingested by loggerheads. Further, with the target species being swordfish, the use of both circle hooks and mackerel for bait had no negative impact on the amount of swordfish caught.