NSC Marine Sciences Human Impact on the Marine Environment: SEABIRD BYCATCH

Many species of

Question

SEABIRD BYCATCH

Many species of seabirds are facing the risk of extinction. Large numbers of birds have been caught as bycatch by long-line fisheries.

Long-line fisheries also influence the food availability of seabirds. Some fisheries may lead to a decrease in the numbers of seabirds by reducing the abundance of their prey. Other fisheries may increase seabird numbers. This happens by increasing seabird prey abundance through the depletion of predatory fish stocks.

Provision of discard and offal can stimulate large increases in scavenging seabird numbers. Desirable reductions in fishery waste may have an unfortunate side-effect of forcing some scavenging seabirds to turn to killing smaller seabirds, with drastic consequences for the community structure.

[Adapted from https://www.researchgate.net/publication/29816290
Impacts_of_fisheries_on_seabird_communities]

An investigation was conducted on similar-sized fishing vessels that only used the long-line method to catch fish. No vessel had measures to prevent/other birds being caught as bycatch. The total number of seabirds captured as bycatch and the species of bird caught is depicted below:

The total number of seabirds captured as bycatch and the species for each fishing vessel

NAME OF FISHING VESSEL

NAME OF FISHING VESSEL             | SEABIRD SPECIES | NUMBER OF BIRDS
--------------------------------------|----------------|----------------
Heart of the Sea                              | Albatross          | 2
                                                  | Petrels                | 4
                                                  | Terns                  | 3
                                                  | Gannets               | 2
Marlin I                                         | Albatross          | 8
                                                  | Petrels                | 12
                                                  | Terns                  | 10
                                                  | Gannets               | 6
Aqua-Bell                                   | Albatross          | 7
                                                  | Petrels                | 14
                                                  | Terns                  | 11
                                                  | Gannets               | 11
Shy Shark II                                 | Albatross          | 16
                                                  | Petrels                | 13
                                                  | Terns                  | 18
                                                  | Gannets               | 17

2.1.1 State the aim of this investigation.

2.1.2 Identify TWO controlled variables mentioned in the text for the investigation.

2.1.3 Construct a pie chart to illustrate the proportions of birds caught by each fishing vessel. Use the total number of birds caught per vessel. Show ALL calculations.

2.1.4 Why would data, such as that found in the table above, be considered as important for ecologists?

2.1.5 How can fisheries lead to the extinction of bird species?

2.1.6 International regulations indicate seabird bycatch may not be more than 50 seabirds in total.

(a) Which vessel in the table does NOT comply with these international regulations?

(b) Suggest a mitigation measure to reduce bycatch in order for this fishing vessel to comply with the international regulations.

SEABIRD BYCATCH Many species of seabirds are facing the risk of extinction - NSC Marine Sciences - Question 2 - 2022 - Paper 2

Worked Solution & Example Answer:SEABIRD BYCATCH Many species of seabirds are facing the risk of extinction - NSC Marine Sciences - Question 2 - 2022 - Paper 2

State the aim of this investigation.

Identify TWO controlled variables mentioned in the text for the investigation.

Construct a pie chart to illustrate the proportions of birds caught by each fishing vessel. Use the total number of birds caught per vessel. Show ALL calculations.

Why would data, such as that found in the table above, be considered as important for ecologists?

How can fisheries lead to the extinction of bird species?

(a) Which vessel in the table does NOT comply with these international regulations?

(b) Suggest a mitigation measure to reduce bycatch in order for this fishing vessel to comply with the international regulations.

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