Land of the rising Sunfish

New observations of Sunfish behaviour have revealed an intriguing symbiotic relationship with Laysan Albatross.

When Japanese researchers in the western North Pacific observed a school of Sunfish appearing to actively follow Laysan Albatrosses resting on the sea, they were soon to discover that this behaviour was mutually beneficial. The juvenile Sunfish, measuring about 40 cm across, were heavily infested with a parasitic worm-like copepod Pennella, a kind of crustacean, which held somewhat of an attraction for the birds. It soon became apparent that the albatrosses were feeding on the worms, as one was photographed doing just this.

The observers suggest that this cleaning behaviour may be frequent in the lifestyle of Sunfish, as the fish seem to actively seek out the birds, which then relieve them of their parasitic. the Sunfish school numbered about 57 individuals and were swimming right at the surface, exhibiting no defensive or evasive behaviour. The feeding actions of one Laysan Albatross soon attracted more, including a black-footed Albatross too. Some of the Sunfish appeared to present themselves by swimming sideways next to the birds, the better to show their parasites.

On a pelagic birding trip, Sunfish are often one of the major non-avian attractions a they swim on or near the surface, and it had been suggested that this behaviour might be due in some respect to their parasitic load. It would now appear that this might actually attract seabirds to remove the parasites. sunfish have also been noted to have associations with Sooty Shearwaters for possibly the same reason, and are attended by cleaner fish species.

Sunfish is the largest marine bony fish species, growing up to 2.7 m in length and weighing up to 2.3 tonnes. Laysan Albatross is a wide-ranging seabird in the North Pacific, with an estimated global population of over 1,180,000, though it is classed as Near Threatened by BirdLife International due to historical declines, but there are also signs that there has been a recent range expansion.

Reference
Abe, T, Sekiguchi, K, Onishi, H, Muramatsu, K and Kamito, T. 2012. Observations on a school of ocean sunfish and evidence for a symbiotic cleaning association with albatrosses. Marine Biology DOI 10.1007/s00227-011-1873-6

https://www.birdwatch.co.uk/channel/newsitem.asp?c=11&cate=__11785

New, Higher Estimates of Endangered Humpback Whales in the North Pacific

ScienceDaily (Oct. 18, 2011) — Scientists have increased the estimate on the number of humpback whales in the North Pacific Ocean in a paper published in the journal Marine Mammal Science. The increase follows a refined statistical analysis of data compiled in 2008 from the largest whale survey ever undertaken to assess humpback whale populations throughout the North Pacific.

The number of North Pacific Humpback Whales in the 2008 study known as the Structure of Populations, Levels of Abundance and Status of Humpbacks, or SPLASH, was estimated at just under 20,000 based on a preliminary look at the data. This new research indicates the population to be over 21,000 and possibly even higher -- a significant improvement to the scant 1400 humpback whales estimated in the North Pacific Ocean at the end of commercial whaling in 1966.

"These improved numbers are encouraging, especially after we have reduced most of the biases inherent in any statistical model," said Jay Barlow, NOAAs Fisheries Service marine mammal biologist at the Southwest Fisheries Science Center in La Jolla, Calif. "We feel the numbers may even be larger since there have been across-the-board increases in known population areas and unknown areas have probably seen the same increases."

The SPLASH research was a three-year project begun in 2004 involving NOAA scientists and hundreds of other researchers from the United States, Japan, Russia, Mexico, Canada, the Philippines, Costa Rica, Panama, Nicaragua and Guatemala and was the first systematic survey ever attempted to determine the humpback whales' overall population, structure, and genetic makeup in the North Pacific.

Researchers were able to quantify the number of humpback whales by photographing and cataloguing over 18,000 pictures of the animals' tail, or fluke because the pigmentation patterns on the fluke act like a fingerprint and are unique to each animal. Scientists determined population numbers by comparing photographs taken in northern feeding grounds (around the Pacific Rim from California to Kamchatka) compared with matches of the same animals in the warm tropical waters of southern breeding areas as far as 3000 miles away.

"This latest revision to the study provides an accurate estimate for humpback whales in an entire ocean that could not have been possible without researchers working together to pool data," said John Calambokidis, senior research biologist and co-founder of Cascadia Research. "While populations of some other whale species remain very low this shows that humpback whales are among those that have recovered strongly from whaling."

http://www.sciencedaily.com/releases/2011/10/111018131341.htm