Concept of Ecosystems

The marine ecosystem includes the oceans, the inter-tidal zone along shorelines, river mouths, lagoons and the seabed. Within that sphere, a system exists where minute plant life supports the lowest level of animal life, which, in turn, supports a longer chain where animals on one level are the prey (food) for those on higher levels. Thus each level is interlinked with other levels. Most ecosystems are finely balanced; therefore any disturbance of the system will upset this fine balance and can cause a failure of the system. Within marine ecosystems is a large diversity of species.

The Marine Food Chain

Like most food chains, the marine food chain is delicately balanced. Marine life depends either directly or indirectly on phytoplankton (B) on which zooplankton (E) prey. Within the food chain, each of the diverse forms of marine life are predators on lower order creatures and they are prey for higher order predators.

• Birds (A) feed on small fish species (D). They can form prey for seals (H) or sharks (I)
• Whales (C) prey on forms of plankton (E)or smaller fish species (D).
• Seals (H) prey on a wide range of fish – pilchards (D) or tuna (G) – but form the main prey for sharks (I).
• Crabs (K), crayfish (L), other bottom feeders and even filter feeders (J) play an important role in the marine ecosystem as they “clean up” the seabed, eating all remnants of other creatures. (See the diagram below.)

The need for safe shipping practices that aid conservation of marine resources

The role of shipping in marine conservation is to adhere strictly to the international prohibition on dumping toxic, oily or non-biodegradable waste overboard. Records have to be kept on board each ship regarding the stowage and dumping of any material, and failure to keep proper records will result in prosecution of the offenders and a fine for the ship.

However, all responsible shipowners and operators will not want to harm the marine environment in any way, and, in many instances, they have been the leaders in promoting the Clean Seas concept.

Management and protection of marine resources

Because all marine life forms part of the marine food chain, strict control measures are implemented to prevent too many of one species being caught by the fishing industry, thereby dislocating the food chain and perhaps, destroying it completely. These measures include

• quotas (allowing only a certain number of marine creatures to be caught by a person per day, or fishing companies are allowed to catch a certain tonnage of fish),
• restricting fishing of certain species to the non-breeding season;
• limiting the size of fish of a particular species to be caught (this prevents young fish from being caught and helps to preserve species for future breeding);
• restricting the size of the mesh in nets (this allows smaller fish – future breeding stock – to escape);
• banning fishing in certain areas (the creation of these marine reserves allows undisturbed breeding of fish and assures future fish stocks.)
• creating artificial reefs by sinking old ships or by dumping clean rubble (this creates a habitat that is conducive for sea creatures to live and breed.)

By disobeying international or local fishing regulations, greedy individuals or companies endanger the survival of certain species of fish, and put at risk future fishing stocks. That could put at risk a vital food source for many.

Fisheries agencies undertake patrols as sea and also ashore to try to prevent the contravention of fishing regulations.