Before commencing an observation period, the observer should assess the suitability of

conditions for recording higher predator observations.

- Firstly, what is the survey vessel''s current activity? If engaged in fishing or other

sampling, it is not possible to conduct a meaningful survey. Ideally, the vessel should

be steaming on a set course at a constant speed (greater than 5 knots, ideally 10+

knots) before the starting observations.

- Environmental conditions influence the detectability of many species and therefore an

assessment of the prevailing conditions is required. Wind speed and direction, sea

state, swell height and direction, cloud cover, precipitation and the intensity of sun

glare can all influence the quality of the data collected. All these variables are

recorded prior to the start of each observation period and whenever they change

during an observation period. If conditions are unacceptable (sea state greater than 6,

heavy snow or thick fog) do not start surveying.

- Environmental conditions (particularly wind direction and sun glare) will determine

which side of the vessel is observed. The observer should stand outside, where vision

is unobstructed, the bridge wings of the FPV Pharos SG provide an adequate viewing

position.

- Following the commencement of the survey, the observer should continuously scan

the 300m wide transect to a distance of at least 300m ahead of the vessel. Any

animals present should be detectable with the naked eye, subsequent use of binoculars

can be useful to confirm species identification, behaviour or prey type. For each

observation, an almost instantaneous assessment of the species, number, behaviour,

distance from the vessel''s track or direction of flight and whether the animal is ''in

transect'' or not must be made and the information recorded on the species form. It is

important to do this as quickly as possible to allow the observer to refocus on

detecting the next animal to be recorded.

- Each record is assigned a time, which relates to a particular 300x300m area of ocean

the highest resolution possible. To aid data entry, it is recommended to use the

snapshot time for all animals associated with a particular snapshot. The snapshot time

is dependant on the ship''s speed, The use of a watch with a repeatable countdown function is a useful way of

alerting the observer when a snapshot is due.

- Seabirds and marine mammals recorded sitting on the water are assigned to one of

five distance bands (A 0-50m, B 50-100m, C 100-200m, D 200-300m, E >300m),

which run parallel to the ship''s track and are measured from the side of the ship. With sufficient data, this allows Correction Factors to be calculated for animals that are undetected in the Bands furthest from the ship''s track.

- All behaviour indicative of attempted or successful foraging is recorded using a

combination of movement, searching and foraging codes adapted in part from Harper

et al. (1985) and Camphuysen and Garthe (2004). It was also attempted to identify

prey items, although this was rarely possible.

- For flying birds, the direction of travel should be assessed and recorded. Whether a

bird is recorded as ''in transect'' or not is determined by the ''snapshot''. The timing of

snapshots is determined by the ship''s speed and are spaced at 300m intervals along

the transect. For example, a vessel travelling at 10knots moves 300m every

60 seconds and therefore ''snapshots'' are taken at 60 second intervals. If a flying bird

is within the transect at the time of a snapshot, that record is classed as ''in transect''.

Under most conditions, birds that pass through the transect between snapshots are still

recorded (as ''out of transect''). These records can help determine the age structure of

the population, moult cycles, migratory routes and increase the likelihood of

recording rare species.

Problems and recommendations

- Observers used to collect higher predator data over the relatively short periods covered by

research cruises should have prior experience of seabird and marine mammal surveys in the

southern hemisphere. It is possible for most people to learn the methodology and become

competent observers over a period of several weeks but data collected in the early days or

weeks of the cruise would be unreliable.

- An assumption of both the snapshot and of distance sampling methods is that animals are

detected before they react to the presence of the survey platform. However, for most air

breathing marine predators this assumption is poor. Many species of flying seabird for

example are attracted to and follow ships. This tendency is especially prevalent in the

Procellariiformes (Hyrenbach 2001), the dominant group in the Southern Ocean. Further

complications occur with diving species, such as penguins and marine mammals, which may

move towards or away from the survey vessel whilst submerged. For cetaceans at least this

difficulty has recently been surmounted by the use of double platform surveys (Buckland et

al. 2004). These rely on a second team of observers, who track an animal''s movements in

response to the approach of the survey ship. The rate of avoidance or attraction can then be

modelled and used to correct the primary observers'' results. Similar methods have recently

been employed to investigate the avoidance of approaching ships by flying birds (e.g.

Borberg et al. 2005). A number of more subjective strategies have also been suggested for

identifying which flying birds are following the survey ship, so that these individuals are not

over recorded (e.g. Spear et al. 2004). Despite these complications, abundance estimates of

some species of flying seabirds based on at-sea data accord with estimates from colony

censuses (Clarke et al. 2003). Furthermore, for the purposes of studies of the distribution of

marine predators versus prey or for investigating the effects of environmental correlates,

relative rather than absolute abundance may be used (e.g. Ryan & Cooper 1989, Ainley et al.

1993, van Franeker et al. 2002, Woehler et al. 2003, Chapman et al. 2004, Littaye et al.

2004). The assumption implicit in studies taking this approach is that each species reacts in a

consistent manner to approaching survey vessels.

In addition, it is increasingly recognised that considerable insights can be gained by recording

the behaviour of higher predators at sea, for example to identify foraging areas (Veit 1999,

Camphuysen & Garthe 2004).

- It is clear that there are some issues regarding the associations between flying birds and the

survey base. It is relatively easy to disregard those animals that persistently form close

associations with the vessel, Cape and giant petrels are particularly notable ship associates.

However, most species of flying birds will associate with the vessel to some extent and

whether a bird is recorded or not can become subjective. Throughout this project, the use of

consistent methodology and observers will help to standardise the recording procedure. A

detailed description of the method used will help to maintain consistency on future cruises.

- Ideally, two experienced observers should be used in tandem. Working in shifts, this would

allow continuous coverage even in mid-summer when day length can be 18 hours. It would

also allow for a more robust assessment of observer error and ensure standardised

methodology.

- At times the density of animals encountered can be over whelming. To maintain the quality

of the data collected it is possible to switch from recording all animals to just recording those

''in transect''. This would require a new Trip Key whenever the method changes