The Fishy Story Of An Escape Ladder
According to recent news reports in Ontario, Canada a man has had a miraculous escape after falling into the Grand River, the largest river in Ontario. The Grand River serves as a drainage channel for meltwater in Ontario, rising in Somerset Township and flowing through Jackson and Ottawa counties before emptying into Lake Michigan. It drains an area of more than five and a half thousand square miles including more than 150 townships. Although the Grand River has several dams along its length, it is a trout and salmon stream and this is the key to the unfortunate man’s lucky escape – a fish ladder.
In this industry we’re more used to hearing about access ladders and safety ladders than fish ladders. We read and hear so much about ladder safety that we can be forgiven for thinking that ladders are fraught with danger. However, falling into the Grand River is a very dangerous business, especially during winter when hypothermia can set in rapidly. The man who fell was lucky enough to fall into the river near a fish ladder and was able to use the fish ladder to haul himself out of the water.
A fish ladder (which is sometimes known as a fish pass, fishway or fish steps) is a structure built onto or around artificial barriers (like locks and dams) to facilitate the natural migration of diadromous fish. Diadromous fish are fishes which migrate between the sea and fresh water to spawn. Some fish, like salmon, will migrate from the sea into fresh water in order to spawn, while others (eels in particular) will migrate from fresh water into the sea to spawn. This type of migration will involve swimming sometimes hundreds of miles upstream against the water flow. This is probably difficult enough when the river runs across fairly flat land. However, as we are all aware, rivers often flow downhill in series of small waterfalls and this presents the fish with a particular challenge.
Some of us may have seen film and video footage of the way in which fish swim upstream across series of natural small waterfalls. The fish seem to jump across the obstructions in their journey upstream and look as if they’re practically flying through the air! This journey upstream is known as the ‘salmon run’ and the fish must begin their journey in peak condition in order to have the stamina and energy needed to complete the arduous journey successfully. They negotiate waterfalls and rapids by leaping or jumping and salmon have been recorded making vertical jumps as high as 12 foot.
Swimming upstream against the rapids and strong currents is an exhausting business in natural waterways and many of the fish die en route. With the abundance of manmade obstacles that now infests our waterways; some of the routes have become all but impossible for the salmon. That’s bad news for anglers, but even worse news for the poor fish. The salmon being a keystone species in Alaska and the Pacific Northwest – a keystone species plays a critical role in maintaining the structure of the ecological community and affects many other organisms in an ecosystem. This means that the salmon needs to be protected as an important aspect of conservation biology. Part of this protection involves making sure that the fish can still make their way back upstream in order to spawn the next generation by providing fish ladders where the course of the waterway has been altered my man so that the fish can still swim upstream to their spawning grounds.