Something's Fishy about Fish Farms

Updated: Jan 3

UPDATE: Email Minister of Fisheries, Bernadette Jordan, to thank her and tell her you support her decision in phasing out fish farms in the Discovery Islands: bernadette.jordan@parl.gc.ca

In a world where we are overfishing the oceans, one would think fish farms are the solution to feeding people and not depleting ocean resources; however, fish farms are usually more problematic than they pose solutions. From what is being fed to farmed fish, to how fish farms impact the environment, fish farms are not the answer to a problem, but rather an additional and unneeded problem. This article will focus on salmon and the fish farms in the Discovery Islands of British Columbia.



Photo: Alexandra Morton


Let's focus on hatcheries for a moment. Hatcheries raise larval and juvenile fish to later either supplement a wild ecosystem or transferred to fish farms so that they can grow to adult size to later be harvested and consumed. We will highlight the rapid evolution of egg size in captive salmon, in order to portray the ecological impacts raised fish can pose on an ecosystem. First, in many animals, maternal fitness is defined as the female's egg survivorship multiplied by the female's fecundity. Fecundity is how many eggs a female can produce. Secondly, if a female lays small eggs in the wild, those eggs will have a low survivorship, as they are easily consumed by predators; however, eggs that are larger propose a lower fecundity in females.


In these salmon hatcheries, being closed -- no genetic input from wild populations -- has led to a higher fecundity in females; due to a lack of predators, females' egg sizes have decreased from 1996 to 2000. So what does this high fecundity but decreased egg size mean for the wild populations of salmon that were supplemented during these years? Wild salmon have decreased maternal fitness, and thus decreased egg survivorship, as a result of breeding with the supplemented raised salmon, due to their eggs being smaller and more susceptible to predator consumption.


For fish hatcheries, this is the outcome: rapid evolution to decreased egg survivorship in the wild.


We just described why raised fish pose more of a threat to wild populations. So then let's just consume farmed fish instead and forget supplementation; that's clearly a better alternative, right? Well, not exactly. One of the biggest ecological concerns with fish farms is this: fish farms were introduced to reduce the amount of seafood we fish out of the oceans; however, the resources needed to feed fishes in farms comes straight from the ocean, only adding to the problem of overfishing. Some fish, like salmon and tuna, need to consume up to five pounds of fish for each pound of their body weight. In addition to raised fish being unsustainable for our oceans, some are born with mutations too gruesome to mention, as per a reliable source within Laich-Kwil-Tach family of tribes, and fed contaminated fishmeal. Farmed salmon are fed from a global supply of fishmeal and fish oil created from small, wild fish; studies have shown that these small fish are the source of polychlorinated biphenyls, or PBCs, in most raised salmon. In three independent studies scientists tested 37 fishmeal samples from six countries and found PCBs in nearly every sample (Jacobs 2002, Easton 2002, and CFIA 1999). Furthermore, PCBs buildup in salmon 20-30 times the amount in their environment and their fishmeal (Jackson et. al 2001), so even low concentrations of PCBs in their feed can become an issue for human health.


Moreover, farmed fish are put under stress and unhealthy living conditions, which not only affect them, but affect us and wild populations of fish that surround them. Fish farms that use sea pens means these raised fish are affecting the surrounding ecosystem in which the pen resides in. In fact, wild juvenile salmon are infested with sea lice due to fish farms (Morton et. al, 2008).


Alexandra Morton, author and independent biologist, and others have collected wild sockeye salmon samples surrounding fish farms in the Discovery Islands. Fish farms are basically rapid breeding grounds for sea lice which affect both raised and wild fish/salmon. Sea lice infected salmon have a higher chance at mortality; in fact, heavy sea lice infested wild, juvenile sockeye salmon are associated with decreased stomach fullness, meaning sea lice reduce their ability to survive (Godwin et. al, 2017). Morton states 99% of wild, juvenile salmon that swam through the Discovery Islands last spring were infected with high levels of sea lice -- levels known to reduce their survival.


Mean relative stomach fullness (±SE) for fish in both infection categories of each collection. Each vertical pair of points (one grey, one white) constitutes a single collection (Godwin et.