TRASNA Blog – Day 7

TRASNA Blog – Day 7

Written By
William Hunt
Research Support Officer
MaREI Centre for Marine & Renewable Energy
Environmental Research Institute, University College Cork, Ireland

May 18 2016
2038 UTC
Air temperature 8°C
Wind 21 knots from West
Sea State 4m

Hello folks and welcome to today’s blog post. My name is William Hunt and I’m the resident marine mammal observer (MMO for short) aboard the RV Celtic Explorer during the transatlantic crossing. I work for the University College, Cork at the MaREI Centre for Marine & Renewable Energy on a project aiming to collate existing data on the distribution and abundance of cetaceans in Irish shelf waters. We then identify data gaps within this knowledge base and will seek to fill in those gaps by sending out observers (i.e. folks like me) to record sightings aboard vessels of opportunity operating within Irish waters.

My role on board is to record any sightings of large marine megafauna encountered throughout the survey, including cetaceans (whales & dolphins), pinnipeds (seals, sea lions, walruses), turtles, sharks and other large fish such as sunfish and tuna. I spend most daylight hours cooped up in the crow’s nest, the highest point on the vessel, scanning the sea surface below for any sign of disturbance that may indicate the presence of animals. Splashes, whale blows, birds circling overhead are all signs that animals may be nearby and on a good day some of these cues may be seen 6-8km distant. Or at least, that is the goal: weather conditions during this crossing have not quite been playing ball with high winds and thick fog often reducing visibility- if not preventing watches altogether.

However, our trip began with a rather delightful send off: as we passed through the narrows we were waved off by 2 minke whales (Balaenoptera acutorostrata), a group of 4-5 harp seals (Pagophilus groenlandicus) and a humpback whale (Megaptera novaeangliae). Our sightings since then have been few and far between but have included sperm whales, a group of possible white-beaked dolphins (Lagenorhynchus albirostris), a fin whale (Balaenoptera physalus) and groups of long-finned pilot whales (Globicephala melas), including one group associating with bottlenose dolphins (Tursiops truncatus). Today brought heavy fog which limited visibility to <800m for much of the day- but it also included 2 sightings of multiple humpbacks both at the start of survey and at the very end. The forecast for the final few days of the crossing is mixed but we hope to report back a number of sightings in the coming days as we crossing into the Irish continental shelf.

Being aboard a vessel engaged in the high resolution mapping of the seabed is a good reminder of the intrinsic links which connect the various systems present within the oceans. Geological and oceanographic processes drive both the formation of marine habitats &  the distribution of nutrients in the ocean. It is this distribution (along with the input of energy filtered down from sunlight and at hydrothermal vents) that determines the location of viable ecological communities. Thus, accurate, high resolution maps of bathymetry and seafloor geology are of great interests to marine ecologists. Through them, it is possible to highlight potential areas of great importance to various groups of animals, including cetaceans: locating deep sea canyons and mounts enables better decision making when determining which areas to target during survey effort, allowing for a better allocation of limited resources and better informing management decisions.

On that note, I’ll sign off for the evening. I’ve a feeling the seabird folk will be soon on to update you on their exciting times!

Minke whale surfacing outside St. John's harbour. ©William Hunt/UCC

Humpback whale surface on May 18th. © William Hunt/UCC

Harp seals outside St. John's. © William Hunt/UCC