Tuesday, March 2, 2010

A few fish we have met and et.

Sierra or Spanish Mackerel, Scomberomorus sierra. Fantastic. Interestingly, recent work on the visual adaptations of this fish suggests that when it is young (larval stage) it has only rod photoreceptors in its eyes. This will allow vivid colour vision but little visual acuity. That is, it can see farther into the color spectrum that other fish (and us) but the image will not be very clear during low light levels. It is hypothesed that these fish may exploit a unique food resource when they are young that requires different visual capacities to detect, then upon maturation, they move into a more commonly exploited food resource that is best visualized by having both rod and cone photoreceptors. I admit it would be an ill- supported hypothesis to suggest that it is this difference in nutrient acquisition during development that is causal to the increased flavor of this fish during its adult life stage. But it was in fact the testiest fish we have eaten so far! Clearly more research into this phenomenon is required and the next one I catch will be entirely eaten as ceviche.

The black skipjack, Euthynnus lineatus. Picture a fish with red steak- like meat. When I butchered it, it felt like I was cutting up fresh beef roast. Interestingly, this species has been used as a model organism to study how it, and other large ocean predatory fish like the tunas, are in fact warm-blooded. That is, they can maintain a core temperature that is higher than the surrounding water. They do this by two basic mechanisms; 1) by having a hemoglobin (blood protein) that maintains oxygen affinity despite being warmed up by the fast actively swimming muscles and 2) having a central blood heat exchanger, that passes the warm, but oxygen-depleted blood past the colder oxygen rich blood to warm it up before it reaches the core of the body. This all helps to keep the animal very active despite ocean temperature fluctuations, which is useful for top level predators. Not the tastiest fish we have eaten but certainly beautiful to see

Mahi Mahi or dolphin fish, Coryphaena hippurus. Beautiful, fast and as one fisherman we met said, “basically the piranha of the ocean”. This has been on my checklist of things to see and do (and catch and eat) while I am here on this planet. So tasty.


  1. I can say that I've eaten Mahi Mahi but not ever seen one, internet or otherwise (until now). From your pictures though, their heads certainly look like the alien's from "Aliens"...do they shoot out little inner-mouths to catch other fish??

  2. I volunteer my ceviche testing services...mmmm...

  3. Mike you are such a geek, I love the descriptions.
    I hope to see on you skype soon. On my side I just got and iphone and am looking for a house. I have to stay at my work for another 3.5 years anyway and need a place to live. I am getting sucked by the city life, but hopefully in 4 years will free myself from all of it and join your travels.
    Hug for Hyo