Specialist Wildlife Research Projects

SEA LIFE SURVEYS RESEARCH

Recording Sightings

LOGGER is a computer program written by Lex Hiby and Phil Lovell (Conservation Research Ltd) for the collection of opportunistic data in real time on a portable IBM PC on the boat. It provides a means of collecting detailed information on sightings, effort, environment and acoustic data.

Each section contains a number of fields into which data can be entered. Several fields have a list of codes available which appear as a menu on the screen when prompted, so that operator can choose the appropriate code. Some fields contain data generated by the program e.g. date, and other fields may receive data direct from instruments connected to the serial port such as positional data from the GPS navigation system. Environmental data is updated every 15 minutes.

Data is stored in Paradox-compatible data files (Paradox is a database program). A companion program called SHOWDATA plots tracks, sightings and effort on a map of the survey area. For the analysis of abundance and distribution of cetaceans the results are presented by dividing the survey area into cells (or squares) small enough to help to avoid effort being directed within this cell. If searching effort is directed within a cell then this is recorded. For each cell the sightings are divided by effort to show the distribution of cetaceans. The abundance in each cell is summed to give a measure of overall abundance. Measures of effort can simply be the miles steamed on effort in each cell. However, LOGGER collects data to allow for other factors to be considered such as number of observers, voyage type, search status and environmental factors which may influence the number of cetaceans sighted.

LOGGER thus provides a means for automating the input of data collection where possible and also has the facility to check for errors. It helps to impose a predetermined survey protocol on the boat which is especially important for whale-watching ventures that have teams which change within and between years and has proved to be a vital tool for Sea Life Surveys.

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Environmental Database

The environment project is one of the most complex and yet fundamental components of our research aiming to compile an environmental baseline for the research area. With continual monitoring, following a consistent protocol, it should yield results that will enable us to monitor any environmental changes and thus help continually assess the ’health’ of the area.

The main section of Logger – on-board computer database – is devoted entirely to environmental data collecting, some of which is automatic from on-board sensors but mainly involving manual input. The automatic data consists of: –

1) Depth: This is entered every 10 seconds from a depth sounder thus allowing us to draw up and study the topography of the sea bed particularly in cetacean feeding areas.

2) Wind speed & direction, boat direction & water temperature These are updated from sensors every 15 minutes.

3) Positional information is collected from the GPS (Global Positioning System) satellite navigation computer every 4 minutes. The frequency of data input can be adjusted to 1 second for projects needing greater accuracy.

Every fifteen minutes the computer demands manual input of data. This data is always entered by the same person thus helping to give some consistency to the assessment of data. There are sections for meteorological data, sea state, tide, numbers and types of shipping, bird counts, and plankton/fish scattering levels. At the same time the effort and voyage status are updated by the same operator.

There is a wealth of useful data stored in the environmental database. Correlations between cetacean behaviour, birds, tides, and position being a rather fundamental question to look at. Analysis is ongoing.

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Minke Whale Surfacing Rates

One of the few behaviours that can be collected quantitatively in the field are surfacing rates. Cetaceans breathe air and to do so they must come to the surface. The rate at which they surface thus represents their respiration rate and because this changes according to their activity, surfacing patterns give us clues to a particular behaviour such as whether a whale is travelling, resting or feeding. Measuring surfacing rates could be particularly useful in assessing whether or not whales are being disturbed.

Data on surfacing patterns is also essential for correctly interpreting many types of visual surveys such as those conducted by the International Whaling Commission to estimate minke whale populations. Because whales are only visible when they surface knowledge of surfacing behaviour allows an estimation of the proportion of whales that are actually visible within a field of view to be calculated.

Precise recordings of surfacing rates have been collected from individual minke whales off Mull since 1989 by Sea Life Surveys with the aim to obtain a better understanding of surfacing behaviour. Preliminary results to date show that the mean surfacing interval has not changed significantly between years remaining at about 83 seconds. Surfacing intervals do not change with the time of day or with the state of tide. There is however a marked change in mean interval through the year with dives getting shorter as the summer progresses from a mean of 100 seconds in May to a mean value of 63 seconds in September. The cause of this is unknown. Contrasting patterns of dive times are also seen when whales exhibit different behaviours.

This study has enabled a baseline dataset to be established against which future fluctuations can be compared and to allow Sea Life Surveys to assess how surfacing behaviour affects the reliability of visual population estimates.

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Photo-identification of the minke whale

The aim of the photographic study is to evaluate the potential for identifying individual minke whales by using fin shape, scars and pigmentation patterns. and whether this could provide some insights into the ecology of the minke whale in the coastal waters around Mull.

A photographic database has been collected since 1990 and on analysis 74 individual minke whales have been identified and catalogued. Thirty-five of these identified whales have been resighted with the greatest number of resightings for one whale being 27 spanning 9 years. Of the 35 that have been resighted 25 have been resighted in different years which shows that whales are returning year after year to the same area showing site fidelity. Within years some whales are resighted in different months of that year and thus appear to be seasonally resident.

Plotting the sightings of the minke whales reveal what appears to be a shift in distribution throughout the season within the survey area. This could be due to changes in the prey distribution or due to a switch in the prey consumed by the whale later in the season.

This study has shown that photo-identification is a feasible technique for the minke whale in the coastal waters around Mull and that from this some important aspects of life history patterns can be understood.

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Range Tracking -A Feasibility Study

Jonathan Gordon (IFAW) has developed a simple technique for measuring range of cetaceans from survey vessels using photogrammetry. This involves measuring the perpendicular distance between the whale and the horizon on a photographic image. The angle that an object floating on the sea subtends with the horizon is a function of the height of the observer and the range of the object, so by knowing the focal length of the camera lens and the height of the camera above the sea level when the photograph is taken, trigonometry can be used to calculate the distance between the whale and the observer.

In 1994 this technique of estimating the range was used to measure the geographical track of a minke whale by taking pictures of each surfacing and noting the whale’s bearing. The position of the boat as each photograph is taken is recorded allowing the track of the boat and the whale to be determined. Control experiments were carried out and reveal that up to ranges of approximately 800m the photographic methods appears to be fairly accurate. The study showed that obtaining the tracks of minke whales is a feasible technique.

This technique can be used in future to determine the whale’s movements over a short period of time which may prove useful to study foraging behaviour and also its movements in relation to the boat to investigate the possible effects that boats have on the behaviour of the whales.

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Acoustic Work

Sea life Surveys has been investigating some of the under water sounds of the survey for a number of years. The aim is to investigate the acoustic behaviour of cetaceans in this area and also to investigate the level of noise pollution in the area. The recordings are made using a Sony professional walkman along with a Magrec Hp-30 hydrophone.

Using our sophisticated under water microphone (hydrophone) to listen to porpoises, crustaceans, and maybe dolphins

Successful recordings include those of Risso’s Dolphins which were highly vocal when encountered. Minke Whales have proved difficult however, however in 1994 one recording of a juvenile whale was obtained capturing a very prominent repetitive sound. This recording is of great interest and is believed to be the first made of a minke whale on the Continental Shelf. Until now the acoustic work carried by Sea Life Surveys has mainly consisted of testing the feasibility of recording underwater sounds in our study area. The results to date how that this work has great potential and plans to direct more effort to this project are being drawn up.

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Seabird/Cetacean Association

The survey area is frequented by a variety of seabirds which often gather in large multi-species flocks to feed. Small fish such as sandeels and herring are prey for both seabirds and cetaceans, and birds are often seen feeding in association with whales or dolphins.

The aim of this project is to investigate the relationships between seabirds and cetaceans to determine which species most commonly associate and which might be benefiting from the relationship. For example, one species might use another to locate prey or cetaceans may drive fish upwards and make them more available to surface-feeding birds. Much of the data is yet to be analysed but preliminary findings indicate significant differences in bird species composition associated with different species of cetaceans or where cetaceans are absent. Kittiwakes and Manx shearwaters were the most commonly recorded birds in association with minke whales while the gannet was the most frequent associate of common dolphins.

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SEAL WORK

Seal Faeces Collection

The aim of this project is to collect grey seal (Halichoerus grypus) and common seal (Phoca vitulina) faeces for dietary analysis by the University of Aberdeen.

There is much controversy over the potential effects of grey and common seal populations on commercial fisheries. Seals could cause damage to the fishing industry by eating commercial species or instead benefit it by eating the predatory fish which in turn feed on marketable species. Past studies have shown that seals feed opportunistically. There is a great deal of seasonal and geographical variation which is largely dependent on the abundance of prey species. The composition of seal diets can be assessed by the analysis of their faeces. Undigested skeletal remains, in particular fish ear bones (otoliths) and squid beaks, reveal the identification of prey species and enables an estimate of the proportion of each species in the diet. Faeces collected at a haul-out site will most probably be derived from seals which have fed relatively close to that site, although this is not always the case. Seals will often defecate at sea. A number of samples have been collected and are currently being analysed by Aberdeen University.

Pressure is mounting for the resumption of an annual seal cull. Sea Life Surveys is committed to the collection of seal faeces so that the dietary analysis can continue to add accurate and important information to this controversial debate.

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Video Footage

Since 1993, video records have been made of various different types of encounter while at sea. Footage has been recorded both above and under the water. Video footage was recorded using a Sony Handycam Hi-8 video camera recorder and Fuji Hi-8 Metal films tapes.

Footage gathered so far shows that video may be useful in the study of animals’ behaviour. We have visual evidence of minke whales associating with the boat, breaching, travelling and lunge feeding; of common dolphins bowriding, feeding and travelling; of Risso’s dolphins displaying, feeding and travelling; and of basking sharks feeding. Video also appears to have great potential for investigating the social structure of groups of animals, notably orca and Risso’s dolphin where individuals can be more easily identified. We also use video to record aggregations of sea birds to investigate how these associate with cetaceans.

We have often attempted to film underwater when minke whales have been associating with the boat. We have captured several very clear images of whales swimming under and around the boat. With better equipment (i.e. a hull mounted wide-angle swivel camera with monitor and recorder in the wheelhouse), much information could be gleaned from more underwater filming. It may be possible to sex individual whales (impossible from surface observations) and would give a much clearer picture of the behaviour of whales and dolphins when associating with the boat.