These are the lecture notes from the first lecture of my Marine Ecology course (BIOL 462) at UNC last fall. I dumped Blackboard and just started using WordPress to share lectures with my students. It works pretty well, but moving all my lecture content from PowerPoint to WP was a pain (especially for my TA). Benefits include greater ease in incorporating multi-media and outside resources via links and no need for students to download massive PDF or ppt files. And you can also share lectures with the world! Speaking of digital teaching resources for marine ecology, check this out.
Required readings for this lecture: Two articles on declining tuna (here and here and go here if you don’t know anything about bluefin tuna). Also, as supplemental reading, take a look at some of the other stories on fishing at SeaMonster here.
One criticism of the IUCN evaluation process and of the study findings is (from here):
Their concerns focus on the IUCN’s “rate of decline” criterion. This compares the rate at which a population is decreasing to the age at which individuals in the population reach sexual maturity (between 5 and 20 years for tunas). The team describes two cases where uncritical application of the rate-of-decline criterion could lead to misleading threat assessments for tunas and billfishes. One is when a population maintains a low but steady level following an earlier precipitous drop due to overfishing. Uncritical application of the rate-of-decline criterion in this case would underestimate threat by placing the population in the “least concern” category, when it may well be vulnerable to extinction in the long term due to genetic effects and natural fluctuations.
The second case would overestimate the threat to a population. This could occur if the IUCN rate-of-decline criterion were applied to a previously un-fished or “virgin” stock that had been quickly culled to a level matching its “maximum sustainable yield” — the goal of fishery managers attempting to ensure the largest on-going harvest. Rapid depletion of a population to its maximum sustainable yield — typically 40-50% of the virgin stock for tunas — would place it in the vulnerable category on the IUCN Red List, directly contradicting a fishery manager’s view that this is a well-managed and sustainable fishery.
Ode to the Stellers Sea Cow
Now on to bluefin tuna
Bluefin landings, from the NOAA bluefin tuna fact sheet (here)
note the live links to the audio about this, just click on the picture!