Impacts of Fishing on Ecosystems & Trophic Structure

Changes in fish communities (inc. benthic)
1. Changes in community structure - k vs r selected
2. Changes in diversity - some species more vulnerable to fishing
Large size top piscivorous predators more valuable - lower value smaller herbivorous species
1. Reflected in global landings statistics
2. Fishing down the food web
Reduction in predatory pressure leads to increase in prey populations (if top down)
1. Spiny lobster couldn't control urchins anymore due to being heavily fished. Explosion of urchins, so doesn't allow kelp to regrow after winter storms.
2. Keystone species - ecosystem forming species - potential loss of whole ecosystem
Reduction in competitive pressure
1. Increase in competitive species
  1. E.g. Jellyfish population in Black Sea
2. Dramatic shifts in community structure
Local organic enrichment - discards and trawler damaged animals
1. Increases in scavenging species
  1. E.g. crabs
2. Anoxia - not a massive issue
3. Increase in seabird numbers
  1. Some species benefit by feeding on discards

Resource summary

	Created by Madison Burt over 10 years ago