Fishes play a very important role in the ecosystem of Canada’s rivers and lakes. If we talk about the lakes, fishes basically redistribute and transport the phosphorus. Apart from it, they redistribute as well as transport the essential nutrients between the deeper bottom zones, pelagic and shores. Well, due to the endless exposure to the water conditions, fishes are considered as excellent indicators of ecological as well as biological integrity. You might be surprised to know that fishes are members of a dynamic, heterogeneous and vast group. It is basically a group or cluster of vertebrates. They live in a wide range of aquatic habitats. Anyway, if we talk about the species of fish, they are greater in numbers than all the vertebrates combined. According to a survey, almost 1200 different species of fishes that are native in nature are found in Canada’s rivers and lakes. Most of them are residing in the marine waters. If we talk about the number, it can be 990 different species.
If we talk about the names of species that are found in Canada’s rivers and lakes, they are Gnathostomata and Agnathans. Fish species that do not have jaws are called Agnathans. Lampreys and hagfishes belong to these species. On the other side, fish species that have jaws are called Gnathostomata. Talking about the Gnathostomes, it consists of five different lineages. They are Sarcopterygii, Actinopterygii, Chondrichthyes, Acanthodii and Placodermi. If we talk about the Chrondrichthyes, they are actually cartilaginous fishes such as rays and sharks. Ray-finned fishes are called Actinopterygii. Flatfishes, perch and salmon are some examples of this species. Lobe-finned fishes are called sarcopterygii. It includes lungfishes and coelacanths. Tetrapods also come under this category. Some are of the opinion that tetrapods have come from those sarcopterygian fishes.
Colour and Form
Fishes come in different colours, sizes and shapes. They basically range from globular forms to string-like lengths. If we talk about the forms, they come in different forms- from a snake or leaf to a lumpy rock. Talking about the size, it can be anything from 8-19 mm to 12m. In the rivers and lakes of Canada, the size of the smallest fishes such as sculpins, darters, and minnows cannot exceed 9cm or 10cm. Some might exceed 5m such as basking and white sharks, thresher and white sturgeon.
So, this is all about the essential species that make up Canada’s lakes and rivers.