for cetacean research
Dr. Adriana Vella
Cetaceans - An Introduction
Whales, dolphins and porpoises are collectively known as cetaceans. There are approximately 79 species currently recognised and it is very likely that new species will be discovered in the future.
The variety in shape and size is wide, ranging from tiny dolphins just over 1m in length to the Blue whale (Balaenoptera musculus), which is typically 25m long and is one of the largest animals ever to have lived on earth.
What is even more interesting is that their variety does not stop there. In fact variations in their behaviour, social life, feeding habits, distribution and abundance, life histories, habitats have been observed.
The cetacean diet is an excellent example. Diet often depends on their size, whether or not they have teeth, and various other factors. Most of the larger whales feed on huge shoal of fish or tiny shrimp-like creatures such as krill, while dolphins and porpoises tend to catch individual fish or squid. Other less common, prey items include octopuses, molluscs, polychaete worms, crabs, turtles and marine mammals, including other cetaceans.
An other important feature of cetaceans
apart from their variety, is their affinity to man!
As all mammals, including humans, they are warm blooded, breathe air, and give birth to live young. Also cetaceans usually give birth to just one young at a time. The little new-born is immediately assisted by the mother or an 'assistant' in order to swim toward the surface for its first breath. Indeed the mother will supervise and teach the young for many years. Apart from these basic biological characteristics, cetaceans show other features which reflect this affinity with man.
1. They have a large brain to body ratio (0.25 to
1.5 % in dolphins depending on the species which compares well with the 1.9 %
in humans and is significantly higher than other mammals), which is reflected
in their complex social and communicative abilities. Furthermore, the neo-cortex
of the brain, the part with which we create, innovate and reason covers 98 per
cent of the dolphin's cortex higher even than man. However it is also much thinner.
Also brain features show great variation between cetacean species (Evans, 1987).
(Jerison, 1983, 1978 and 1980) considers that the encephalisation quotient,
EQ (the ratio of the brain volume to body surface area) is a better measure for
comparing the development of mental processes between species. These show an increase
both evolutionarily (from approximately 1 for Eocene cetacean skulls to 2 for
Miocene toothed whale fossils) and between living taxa from 1.5 in a river dolphin
to 5.6 in the bottle-nosed dolphin. The EQ of humans is approximately 7.4 that
of chimpanzees is about 2.5 but almost all other mammals are substantially lower
Thus from what I have said so far it is obvious that Cetaceans are not only a varied group of animals, cetaceans are also unique in their adaptations, biology and behaviours and thus may furnish mankind with answers to many questions relating to the effective utilisation of the marine environment and resources by another group of mammals - HUMANS. We may also find that Cetaceans may be useful to man in many more ways than those noted to date.
Cetaceans - A group of animals in danger
Unfortunately Cetaceans suffer from several direct and indirect human influences on the marine environment (IUCN Red data book 1991). The most common include:
1. Whaling and other forms of hunting,
capture in fishing nets:
with fisheries for food:
4. Human disturbance:
5. Capture for captive confinement,
6. Habitat destruction and marine pollution (Oil, Chemical
wastes, Sewage, Rubbish) have all taken their toll:
Due to all of the above, some cetacean species are now in serious trouble and others have all but disappeared from many of their former haunts. Not surprisingly, the IUCN Red List of Threatened Animals compiled by the World Conservation Monitoring Centre in Cambridge, UK, has listed all the species of dolphins and whales.
Each of the problems listed would deserve a talk of its own. However being aware of these problems may help us understand why research and monitoring of marine resources and in our case Cetacean populations becomes vital in checking the extent of effect of one or more of these problems on the perpetuation of the species.
Cetaceans are relatively difficult animals to study in the wild. Many species live in remote areas far out at sea. Some species are fairly shy and elusive and will avoid boats altogether. Several larger species divide their time between separate feeding and breeding areas, which are often hundreds or thousands of kilometres apart. Not surprisingly, for many years the only information we had about them came from dead animals that had been washed ashore or killed by whalers or fishermen. Nowadays, however, a number of research techniques are being employed to study the animals in their natural habitats and exciting new discoveries are being made all the time (Simmonds & Hutchinson 1996).
Some of these contemporary
research techniques involve:
In each of these techniques the unit focused on is usually the population which needs to be monitored and studied closely in order to understand its viability and persistence in the future. Thus a population's range, demographic dynamics and genetics are increasingly becoming important in assessing the condition of the cetacean population concerned and in planning ways of adequately managing conservation measures.
However apart from studying cetaceans in isolation, cetaceans may be studied in conjunction with fish stock assessments so as to obtain a fuller picture of cetacean populations in relation to their marine environment and more importantly in relation to fishing activities.
It is very important to note that Cetacean studies have been aided by a greater awareness of the general public including individuals making use of the marine resources. With out their collaboration our knowledge today would be scarcer.
From the 79 species known to date, 19 have been observed in the Mediterranean and about 8 of these species are seen regularly, these include (Carwardine 1995; Notarbartolo di Sciara pers. comm.):
Another four species are considered occasional visitors:
Among the other seven regarded as rarely occurring in the Mediterranean, the most common is the:
Unfortunately, local research on Cetaceans has been limited to dead strandings reports and occasional recordings of sightings around the Maltese Islands, mostly carried out by fishermen. Here I would like to take the opportunity to thank those fishermen who have furnished such sighting information in the past and look forward to a greater collaboration in the future. Due to the limited data available, scientific surveys and research are required to better appreciate the status of the cetacean populations in this region of the Mediterranean. Here there is a role to play by local people of every type: fishermen, yachtsmen, ferry personnel, helicopter surveying personnel, sports divers, etc. can greatly contribute toward the first stage of surveying which includes the spotting of specific sites visited by specific cetaceans at specific times of the year. Also information of the general characteristics and numbers of these cetaceans sighted may also be picked up. This type of information gathering would greatly aid research efforts undertaken by myself on local cetaceans. Toward this local research may I advice anyone at sea to forward the following basic information on each dolphin or whale sighting witnessed to the address given below:
Sighting Information :
Location of sighting; size and approximate colour of individual/s; number of individuals; time and date of sighting, distance from boat and type of boat.
Dr. A. Vella, Department of Biology, University
of Malta, Msida, MSD 04, Malta.
Dr. A. Vella is
assisted by BICREF volunteers:
1st: From the little that is known world wide of these animals they prove to be not only interesting from a biological point of view but also interesting to humans for their beauty and friendliness. This is apparent by the number of people (including Maltese people) who find these animals irresistible.
2nd: Due to their highly adapted marine life they respond to changes in it and thus may act as indicator species, aiding environmental monitoring and management.
3rd: As some species are closely linked to fish stocks of economic importance it is vital to understand the underlying linking relationship so as to better control fish stocks.
4th: Unless detailed research is undertaken, it will become very difficult to appropriately protect and sustain cetacean populations around our islands for future generations.
5th: Knowledge is the indispensable foundation on which education and public awareness is to be based. Scientific research is the only reliable means of obtaining such knowledge.
6th: Marine life sustainability requires long-lasting marine processes and dynamics to be respected. Biodiversity, abundance, distribution of marine organisms have taken time to evolve into a neatly intricate functional unit. Cetaceans make part of this unit. Loss in cetacean populations may only aid in creating further imbalances in an increasingly fragile Mediterranean sea.
7th: Cetaceans are fast becoming of touristic and of therapeutic value as more and more people seek their presence for pleasure or for treatment of various psychological problems. However effective utilisation of cetacean populations for such activities need to be preceded and go hand in hand with constant and extensive studies of the populations concerned. This is mandatory in order to minimise disturbance to the cetacean populations concerned.
8th Last but not least, as humans are the major exploiters of marine resources it is their responsibilities to find ways of effectively managing the marine environment. Just as a farmer takes care of his land if he wants it to produce its crop in subsequent years, so the marine environment has to be taken care of for future generations of users.
Cetacean research - Place for collaborations at National and International levels:
I would like to conclude my presentation by pointing out that the research and management of cetaceans has to be carried out at both local and international level because of the large distributions involved in most cases. This workshop aims at setting up a working framework for local research, monitoring, education, and conservation management. This local framework can then grow to include international working links.
The workshop session in the afternoon gives those present the opportunity to contribute toward increasing our knowledge of local population sightings. Just in the last few months it has been possible to get a good number of valuable sighting information from local fishermen and yachtsmen which clearly stand as testimony that several Cetacean species including whale species do indeed visit the waters around the Maltese Islands and that many local people enjoy collaborating in this way. Thus with a little effort from all those that use the marine resources lots of other valuable information could be gathered aiding environmental and economic national interests.
The most effective conservation strategies for cetaceans will evolve from a combination of well directed scientific research, coupled with an understanding of the political, social, economic and cultural shaping of the problem/s. These studies will required a sound basis of fundamental research on the biology of cetaceans and the influence which environmental and other factors have on their populations.
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