Population counts and determination of the influence of natural phenomena and human activity on the Galapagos sea lions and Galapagos fur seals

An important step towards the long-term preservation of these seal species.

A project of the Charles Darwin Research Station on the Galapagos Islands.

Introduction

In 1979 the Galapagos Islands were the first territory which was declared a World Heritage Site by UNESCO. The flora and fauna of the islands is unique, around 60% of the birds and 90% of the reptiles are found only on these islands. For over 40 years the Charles Darwin Research Station on the Galapagos together with the National Park authorities have strived to protect and maintain this unique natural reserve. The work of the Charles Darwin Research Station is supported by the Charles Darwin Foundation to which the Swiss Association of Friends of the Galapagos Islands belongs.
Two unique mammals of the Galapagos Islands are the Galapagos sea lions (Zelophus californianus wollebaeki) and the Galapagos fur seals (Arctocephalus galapagoensis). Both are endemic (found only on the Galapagos Islands), and belong to the family of eared seals. Whereas the Galapagos sea lions were little hunted, the Galapagos fur seals were very intensely hunted for their fur. At the beginning of this century they were thought to be extinct. However a few animals survived and, thanks to very strict protection, the population has been re-established. Today the populations of both species are estimated at about 40 000 animals, but the last census dates from 1979 and not only have 20 years passed since then but also the islands have suffered 5 El Niños of which 2 were "once-in-a-century" events. The waters in the archipelago are normally fed from the cold Humboldt current and have a temperature of 18 – 22C but during El Niño years the temperature can rise to 32C. This drastic temperature increase causes most fish to seek cooler waters and leave the coastal areas, so depriving the sea mammals and sea birds of their food. The El Niño years have dramatic effects on the sea birds with population reductions of up to 60%. The effects of these phenomena on sea lions and fur seals are still unknown.
Human activities as well as climatic conditions affect the populations of these two seal species. The waters of the archipelago are one of the richest natural reserves in the world. In 1998 the Ecuadorian Parliament recognised this wealth of species with the creation of the Galapagos Sea Reserve which is the second largest sea reserve in the world after the Great Barrier Reef. The greatest threat to the Reserve is uncontrolled and unregulated fishing, and one of the most important problems is the incidental capture of sea lions, fur seals, sea birds and turtles. In order to determine the effect of this capture on the populations of sea lions and fur seals and to work out ways to control and reduce it, the Charles Darwin Research Station on the Galapagos Islands has produced a programme with two main parts. Firstly a detailed survey of the size and structure of the eared seal populations must be made (the last census was made 20 years ago). This activity will be covered by the Swiss Association of Friends of the Galapagos Islands. Secondly, it has to be determined how often and with what consequences sea lions and fur seals (and other animals and birds) are taken in fishermen’s nets or lines. This activity will be covered by the Charles Darwin Research Station. Other activities such as guidance of local fishermen in methods to reduce or avoid such captures are also planned.

Aims of the Project
The aims of the project are to determine the populations of sea lions and fur seals on the Galapagos Islands and to quantify the effects of natural phenomena and human activities on the populations in order to define efficient measures for protection.
For this, the size, structure and distribution of the present population of animals in the archipelago must be determined.
Furthermore, information concerning seals caught in fishing nets must be obtained and simple methods proposed to save these animals.

Planned Activities

1. Planning and carrying out a careful population count over the whole archipelago. These counts are carried out in the animals’ mating seasons between June and December 2001 and 2002. For this, two boats, each equipped with two small inflatable dinghies, will each survey half of the archipelago. Money will be supplied for the transport, equipment and logistics. In addition "sighting forms" will be distributed to various research boats, tourist boats, and fishing boats. All data will be registered, controlled and published
2. Recording of the sighting of animals captured in nets and individual rescue.
   Standard forms to record the sightings will be distributed to tour boats as well as fishing boats and the results collected. Reports of captured animals will be sent on to the National Park Authorities for rescue operations.
   

Starting Date and Duration of the Project
This project will be an important element in the whole marine ecology research on the Galapagos Islands. It will run for two years and will begin in June 2001. After one year a short intermediate report will be made on the state of the project giving first results.

Necessary means (in USD):

Explanation: (1) Two Ecuadorian biologists are occupied full-time with the project. (2) Included are transport costs, insurance, board and lodging for students from Galapagos and from the Ecuadorian mainland. (3) Two boats will be rented (cost US$700 per day). (4) Included here are also the 4 inflatable dinghies. (5) Costs for printing and distributing the data sheets and for the analysis.

Financial responsibility/Partnerships The project will be conducted, accompanied and part-financed by the Charles Darwin Research Station. Project controller is Dr.Hendrick Hoeck, President of the Swiss Association of Friends of the Galapagos Islands, former director of the Charles Darwin Research Station and at present Member of the board of the Charles Darwin Foundation.