Shifting Baselines

Home Forums Due October 8 by 11:59pm Shifting Baselines

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    Greenberg brings up the idea of a shifting baseline and goes on to define it as “every generation has its own, specific expectations of what “normal” is for nature”. As each generation comes and goes, the environment they live in will most likely be changing, causing each generation to have a different idea of what normal will be. Greenberg also makes it seem that a shifting baseline is a negative thing. Does it always have to be? What if the baseline for a population was low and then over the generations started to increase, that wouldn’t be necessarily be negative. If the population is changing to become lower and lower until it’s baseline is critically low, yes that would be negative. Also if the population becomes higher over generations, that can be bad as well, but seems to be more manageable and less of a problem. I’d describe a shifting baseline as a change in what is normal for a species. So if a lower population is normal, thats a shifted baseline, or if new predators are introduced, that’d be a change in what is normal. For northern cod, they were way overfished and continuously herded into a smaller and smaller school. This can cause the fish to adapt to mature faster and try and lay eggs sooner. This can cause a problem because there will be less eggs that a female can produce and less milt that the male can provide so this will lower birth rates. Cod were fished so hard for a long time without people seeing the problem because they only saw the dense schools and didn’t realize there were less and less of these schools.
    Shifting baselines seems inevitable to me, there are so many things changing that can cause the shifting of baselines. Initially I would think the obvious for a decrease in population: start cod hatcheries. This however is very unreasonable because cod are terrible candidates for this process. Then I would suggest a moratorium on the cod fishing industry which has already been put into place and has helped a small amount. One of the problems with cod is that as well as their own decrease in population, their food source had a decrease in population. Maybe a hatchery for the food source of cod could help increase the population of cod and shift their baseline in a positive way.

    Kortney Birch

    I like how you not only talked about a decreasing baseline, but also described how a “shifting baseline” can also be an increase in the population size or in increase in a change. I hadn’t thought of that before. Perhaps a hatchery to restore cod fish could be beneficial, but they would be terrible fish-farming candidates!


    You brought up an interesting perspective about baselines shifting in the other direction. I had not thought about it going in that direction. This especially could be seen when it comes to invasive species. Rather than completely eradicating them a new generation could accept it as a new “normal.”


    I liked how you talked about other ways baselines can shift. I hadn’t thought about an increase in a population also contributing to a shifting baseline.


    I agree with everyone else, you brought up some great points about a variety baselines. A cod hatchery would be difficult though because even if you just hatch the cod when you introduce hatchery fish into a wild environment as fry they tend to become food very quickly for other species.

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Fish and Fisheries in a Changing World