The bottom longline fishery and its use as a source of benthic biodiversity information around South Georgia
South Georgia is a large, old, and isolated oceanic archipelago in the Atlantic sector of the Southern Ocean. It is surrounded by a wide continental shelf which is highly productive, rich in biodiversity and one of the world’s largest Marine Protected Areas. Most of its ~1450 species live on the sea...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | unknown |
| Published: |
2017
|
| Subjects: | |
| Online Access: | https://oro.open.ac.uk/48676/ https://oro.open.ac.uk/48676/1/Full_thesis_OU_Ramon%20Benedet.pdf https://doi.org/10.21954/ou.ro.0000be24 |
| Summary: | South Georgia is a large, old, and isolated oceanic archipelago in the Atlantic sector of the Southern Ocean. It is surrounded by a wide continental shelf which is highly productive, rich in biodiversity and one of the world’s largest Marine Protected Areas. Most of its ~1450 species live on the seabed, many are endemic or at the edge of their geographic ranges, but are still quite poorly known. This UK overseas territory is administered by the Government of South Georgia and South Sandwich Islands and its waters are designated Food & Agricultural Organisation (FAO) area 48.3. They form an important fishing ground for a well established fishery for the Patagonian toothfish Dissostichus eleginoides , a high value fish endemic to the Southern Hemisphere. There are many more fishing than scientific vessels visits to South Georgia and fishing boats, deploy lines at locations too steep or rough for most scientific sampling gear. This thesis investigates the potential for this fishery to be a source of much needed biodiversity information and evaluates how benthic invertebrate bycatch data is collected by fishing observers. After a general introduction, chapter 2 describes and compares the two longline systems (autoline and Spanish system) used around South Georgia. It also investigates how technical changes in the gear imposed through legislation was responsible for one of the best examples worldwide of successful management on reducing seabirds mortality from nearly 6000 birds yearly to almost zero in the recent years. Historical data was used to show how both gear types have evolved and new weighting regimes adopted. Chapter 3 investigated a method to potentially improve collection of benthic bycatch information by observers, by reducing routine workload. An electronic monitoring system (EM) was designed and installed on a longline vessel to record footage of fishing activity. Data collected was compared to that from human observers, which could optimise that during settings by ~89% of the time spent by the ... |
|---|