Where I live on the central east coast of Vancouver Island there’s a sense that spring is just about to start in earnest. Oh sure, there’s been snowdrops out for a while now but they’ve not infrequently been buried off and on in their namesake element so it hasn’t really seemed as though spring has sprung. Just in the past few days though the air has warmed up with no frost overnight at sea level since late last week, and so the season should start to advance quickly now.
Pretty much all wildlife development, plants included, is driven by temperature or more accurately a combination of temperature and time. In science this is quantified by the term accumulated thermal units or ATU’s. I don’t know what the ATU point is for skunk cabbage to bloom, for example, but I’m certain it won’t be long now before their characteristic yellow flowers start to show. I’ve seen some green shoots protruding up from the swampy areas these plants so identified with spring hereabouts like to live in, but it won’t be long before there’ll be highlights of yellow to brighten up the somber coloured woods.
And in the local fish world the first of the salmon fry have started to swim up from the gravel. As usually the first to spawn, this annual phenomenon is led by pink salmon simply by virtue of having had the longest time to develop. The water temperature in many area rivers has been in the low single digits Celsius for several months now so the development this winter from fertilized egg to eyed-egg to alevin and finally to “buttoned-up” fry (as they are known in the fish culture world), has been very slow. Now, with all the yolk sac consumed and no more internal groceries to survive on, hunger will drive these fully formed little salmon up out of their hiding places in the safety of the gravel substrate to find their way in the world, largely a case of eat or be eaten.
Pinks have evolved to have the shortest freshwater residency of any of the salmon, migrating almost immediately downstream and into the estuary and then further out to sea. Perhaps this happens because at an unvarying two years they also have the shortest life history of any of the Pacific salmon species and need to get a move on. It’s astonishing what they can accomplish in that short time, leaving as teeny little creatures weighing approximately 120 to the ounce with the survivors returning about 15 months later typically weighing 3 to 6 pounds, occasionally twice as big!
Following the pinks will come the chinook and chum fry. Most coastal chinook stocks are known as “ocean type” in Canada or “sub-yearlings” in the US and spend about 3 months in the river and estuary after emergence from the gravel before heading into the ocean. One common reference for these fish is “90 day wonders” precisely because of the duration of their freshwater residency. Chum fry exhibit behavior after emergence somewhat between the pink and chinook salmon fry, moving fairly quickly to the estuary but then holding in that environment for sometime to take advantage of the usually favourable conditions there. Driven by the tides reasonably warm saltwater washes in and out of the estuary, combining with the freshwater to generate a food rich environment compared to the river upstream at its least fertile period of the year.
Coho are still in the gravel, mostly at the alevin life-stage. Constrained in movement by their cumbersome yolk sac they have no reason to leave the gravel yet and were they to do so would almost certainly be consumed by one of the numerous predators patrolling the stream. As fish about to start a year or more of freshwater residency before migration to the sea it makes sense that coho have evolved to typically be the last salmon species to emerge from the gravel, as the warming water will in turn be triggering the rise in insect life activity necessary to sustain young coho fry.
I’m thinking that around southern BC there’s going to be a quite staggering number of chum fry emerging from the gravel over the next few weeks, the product of last years bumper chum return. Once the main fall rains ended last year there wasn’t any serious flooding subsequently so with luck survival of the chum eggs was decent. I just hope that the arrival of the chum fry in the near shore marine environment coincides with productive plankton blooms to sustain these billions of little salmon – so many factors to have to go right in order to ensure the continuance of this abundance.
And this mass of new chum fry will do its part in sustaining other creatures like resident trout, pre-migrant steelhead and coho, various diving birds and on up to mammals like seals which are known to feed on dense schools of chum fry working their way down the shorelines.
Further in turn, this fry migration will bring out one of the less numerous of the various homo anglicii sub-species in this part of the world, the estuary and beach fly fisherman. They will be in search of cutthroat trout preying on the pink and chum fry schools and, given the probable size of the essential grocery requirement necessary to support this fishery, 2017 could be a spring season to remember!
Switching briefly to an early spring event already well underway, the herring spawnathon along the eastern seaboard of Vancouver Island and its attendant commercial roe fishery has been in the news, in part sadly for the wrong reason. At the onset of the seine fishery near Comox the Miss Cory capsized for unknown reasons and sank quickly, resulting in the death of one crewman. With the vessel on the bottom in deep water recovery is going to be challenging.
Poor weather has hampered the fishery and appears to have resulted in some of the herring schools holding off from entering the shallows. At the time of writing the gillnet fleet has harvested just over 50% of their allowable catch, with the seiners doing a little better. Much wildlife, including thousands of Stellar sea lions, congregates with the herring, all in all it’s quite the spectacle – search for relevant videos on social media.