The ocean teems with life, above and below the surface. Under the waves in Tasmanian waters at this time of the year are some of the biggest creatures known to nature – southern right and humpback whales – and sailing the winds above them, the biggest of birds, the wandering and royal albatrosses.
The Mercury has reported in recent weeks big numbers of whales on the move from sub-Antarctic seas to calving grounds along the eastern Australian coastline. At the same time the Southern Ocean and Bass Strait has come alive with seabirds of possibly 25 species roaming the waves until the dark Antarctic winter lifts and they return to breeding grounds across the bottom of the earth.
Among them are not only eight species of albatross but petrels, fairy prions, shearwaters, gannets, and white-faced storm-petrels, the latter a tiny bird the size of a swallow which dances across the waves on webbed feet.
The oceans might be a highly productive eco-system awash with life but they do not necessary teem with just one component, be it one species of fish or one species of bird. Ocean life comes together in a complex mix, a balancing of the needs of mammals, bird and fish species in which all components, all species, are in some way linked and connected, reliant for survival on each other.
I have a knowledge of ocean birds – honed during pelagic bird-watching trips out to the continental shelf off Eaglehawk Neck – but have limited knowledge of fish species and their abundance and so I have deliberately stayed out of the current controversy over whether a super-trawler, the Margiris, should be given the go-ahead to exploit redbait and mackerel resources in Tasmanian waters.
I must say, though, I have long held concerns about the by-catch of such huge trawlers and their equally huge nets. My experience of marine mammals and seabirds is they gather, sometimes in colossal number, where the fish gather and it is inevitable that least some of them will get caught up in the nets, although the owners of the super-trawler say escape routes are built into the nets to avoid dolphin and seal by-catch.
Seabirds had been very much in my thoughts in recent weeks because I had planned a ferry trip toMelbourneand, for the return journey, had deliberately chosen a day sailing to view gannets and other seabirds from the ship’s decks.
A bad case of influenza intervened, forcing me to cancel my trip, but there was some consolation when I logged on to my computer for the first time in days. I found a picture taken by a reader of albatrosses feeding off the Tasmanian coast earlier in the year.
Said the reader, Mike Martyn, in his email: “We were tuna fishing near Cape Pillar in April and came across a school of redbait being fed upon by a variety of seabirds and seals. It was quite a feeding frenzy. We stopped and the redbait tried to hide under our boat which made it rather interesting and ideal for photography. There were mainly Buller’s albatross but also shy albatross and Australian gannets.
‘‘This highlighted the importance of redbait as part of the food chain for seabirds as well as other predators and fish.’’
This last point is important in the Margiris debate because we tend to take the view that the ocean’s harvest somehow belongs to just one species, Homo sapiens, and all decisions about fishing only have to take humans and their needs into account. The picture of Buller’s albatross feeding on redbait suggests otherwise.