Tuesday, June 10, 2008

Jellyfish Heaven

It is perhaps fitting that we have received so many wonderful crafted jellyfish for our Northwest Atlantic sea floor display. After all, jellyfish are an abundant source of food for many marine creatures. At 95 percent water, they aren’t packed with nutrients, but the sheer mass of jellies that can be found in one area makes them worthwhile prey for the likes of leatherback turtles, swordfish, salmon and tuna. In turn, many of these jelly-munchers become available as food for other animals – including the voracious homo sapiens.

Alarmingly though, scientists have warned that human impacts - from overfishing to climate change - are creating a sort of jellyfish heaven under the sea. These gelatinous wonders are extremely well-poised to fill important ecological vacancies left by fish higher on the food chain in the wake of disrupted marine food webs. Already, massive and long-lasting jellyfish “blooms” have begun to appear in various places where productive fisheries and diverse ecosystems once existed. These jelly swarms are astonishingly dense, disrupting shipping routes and bursting trawler nets.

As veteran University of British Columbia fisheries scientist Daniel Pauly has long advised, if we don’t change the way we fish, we’ll fish our way down marine food webs and end up dependent on a diet of “peanut butter and jellyfish sandwiches.” Indeed, Atlantic Canadians have already witnessed the beginning of this transition – since cod stocks collapsed, many fishermen have switched to invertebrates like lobster, crab and shrimp.

If you are near Halifax, Nova Scotia, please join the Ecology Action Centre and St. Mary’s University in welcoming intrepid author and adventurer Taras Grescoe, who will be reading from his new book about sustainable seafood called Bottomfeeder on June 11th and 12th. After a year-long sojourn around the globe in search of ethical seafood, he has concluded that we need to “give big fish a break” and eat lower on the marine food chain. While a diet of jellyfish is not likely to feed the world, choosing lower-trophic species such as mackerel, herring and sustainably farmed shellfish can help us to restore the dynamic biodiversity so crucial to ocean health - and to future generations of seafood eaters.

Sunday, June 8, 2008

Happy World Ocean Day!

Thanks on behalf of the Ecology Action Centre and the Loop Craft Cafe to everybody who stitched up a creature feature over the last two months or otherwise helped create our Northwest Atlantic sea floor ecosystem. Another round of thanks to those who came to visit our display on the Halifax Waterfront, where we joined up with dozens of other local ocean-related organizations to celebrate World Ocean Day. It was a fabulous sunny day and organizers counted more visitors than ever this year.

Over 300 school kids visited our Stitchin’ Fish sea floor, taking time to learn all about sea cucumbers, squid, crabs, bubblegum trees and other fascinating denizens of the deep. Unlike the remote floor of the Scotian Shelf, this crafted version allowed for lots of hands-on contact and tactile interactions. We can only hope that this cuddle time with our woolly marine ecosystem will take root in this next generation of fishers, scientists, managers, and seafood consumers – and help cultivate our deep and essential relationship with the ocean...

... because it’s kinda like President George W. Bush once said: "I know the human being and fish can coexist peacefully."

Wednesday, June 4, 2008

A Shark Among the Fishes

Let me guess… as you looked at this photo of a crocheted great white shark, you began to hum the theme from JAWS? That’s probably because this incredible animal, the largest of predatory fish, is also one of the most maligned by Hollywood.

Despite their notoriety, very little is known about the biology and habits of the great white shark, or Carcharodon carcharias. For example, where they mate and birth their young remains unknown. These torpedo-shaped predators are seen only rarely in Atlantic Canadian waters, with sightings and captures reported every couple years in the Bay of Fundy and off southwest and eastern Nova Scotia.

We do know that the great white is solitary hunter that can reach over six meters in length. They have one of the widest habitat ranges of any fish, and can tolerate temperature differences from sub-arctic to inshore tropical conditions. Their sleek evolutionary design has helped them rule the seas for over 400 million years, until humans usurped their role as apex predator, very recently. Many are caught as trophies for sports fishermen every year and even more end up caught as bycatch on pelagic long lines, trawls and gillnets.

A recent study out of Dalhousie University has revealed that North Atlantic great white shark populations fell by 79 percent from 1986 to 2000. They are now classified as a vulnerable or endangered species by many governments, including Canada, but much more needs to change on the water to ensure their survival. Depleted populations may take a long time to recover. Great whites grow slowly, and don’t reach sexual maturity until around 12 years of age.

If you are lucky enough to be in Halifax this Saturday, I’d like to invite you to come down to the Oxford Theatre for a 1 pm matinee showing of Sharkwater. It is a film by Canadian director Rob Stewart that features amazing shark footage and is helping to change our collective societal tune about sharks and ocean conservation issues. This film presentation is part of a weeks-worth of activities to celebrate the Ecology Action Centre’s Ocean Week.

Tuesday, June 3, 2008

One Fish, Two Fish, Unlucky Redfish

Check out this pretty little redfish, quilted by hand by the Ecology Action Centre’s own fisheries scientist, Jennifer Ford. Atlantic redfish, also known as ocean perch or rosefish, are members of the widely distributed Sebastes family, and closely related to the nearly 70 species of rockfish found off the Pacific coast. As you might expect, redfish are usually orange-red to scarlet in colour. They are a small fish, distinguished by their large cartoon-worthy eyes, a boney skull and jaw, and a fan of sharp, bony spines radiating around their gill cover.

“Ocean perch,” a popular market name for redfish, was invented by slippery seafood sellers in the 1930s. As freshwater yellow perch stocks declined, fishmongers responded by substituting with red fish fillets, which are similar in colour and could be sold twice as cheaply. Redfish is still a popular seafood choice in Midwestern US states, where most Canadian catches are sent, often after being frozen and filleted at sea.

Unluckily for the Sebastes family, all species are very slow-growing, late to mature, slow-moving, and easily caught. In the early days of the commercial fishery, redfish were caught by trawling along the seafloor during daylight hours. However, fishermen discovered that redfish move off the bottom at night to feed, and eventually switched to a midwater trawl, which is similar to a bottom trawl, except that it can be adjusted for use at different depths. More recently, combinations of bottom and midwater trawls have been used to allow fishermen to target redfish over a full 24 hour period.

Sadly, redfish populations around Atlantic Canada aren't doing so well these days. As the Department of Fisheries and Oceans (DFO) has reported, landings are down, recruitment is low, and estimates of abundance are substantially down. More sustainable seafood alternatives caught or farmed in Nova Scotia include bottom hook and line caught haddock, trap-caught shrimp, harpooned swordfish, low-density farmed mussels and oysters, rod and reel tuna (except Bluefin), and the ubiquitous lobster.

Monday, June 2, 2008

Children of the Sea Corn

Ganking a crochet technique applied to metal coat-hangers used to protect lady’s delicates from wrinkling, this gorgonian coral was crafted with pipe-cleaners and orange yarn during a marathon of circa-1993 Kids in The Hall episodes.

Primona resedaeformis, known locally as sea corn or rice crispy corals, are some of the most common species of coral found off the coast of Nova Scotia, often in association with Paragorgia arborea, crocheted and blogged earlier here. Like other gorgonian corals, sea corn generally grows in a bushy formation, with thin branching stems extending from a short main trunk. The branches are made up of colonies of individual polyps, which extend sticky tentacles called nematocysts into the current to fish for meals of plankton and dissolved organic matter.

As bottom hook and line fishermen have known for generations, these underwater coral forests provide vital habitat for a wide assortment of marine species, including commercially significant fish like pollock and redfish. The nurturing arms of sea corn offer protection from predation and currents, and even boost the feeding ability of other filter-feeders like brittle stars, who perch in the branches.

Much like our crafted version, Primona resedaeformis grow very slowly. They can live for several centuries, growing only a few centimeters a year. Over time, thin deposits of calcium carbonate, (CaCO3) accumulate on the coral branches, from the built up skeletons of successive generations of polyps. These layers can be examined much like growth rings on a tree, and contain valuable information about climate change, along with its alarming ‘sister crisis’, ocean acidification. (Photo courtesy of DFO.)