Following on from two great posts by John and Albert on Carribean reef fish decline and coral collapse, I thought it’d be worth posting these visually stunning images from a recent publication by Loren McClenechan, titled “Documenting Loss of Large Trophy Fish from the Florida Keys with Historical Photographs“. Through analysis of historical photographs in the Florida Keys, Loren managed to piece together a convicing history of recreational fishing trends over the past half century. Large fish really were more abundant in bygone days: the average fish size caught in 2007 was a tiny 2.3kg, compared with 19.9kg in 1957, and that the average length of sharks declined by more than 50% in the same period. In this case though, a picture really is worth a thousand words.

1a

1957

1b

Early 1980's

2007

2007

igure 3. Species composition of  displayed trophy fish in  1956–1960, 1965–1979,  1980–1985, and 2007 arranged  in order of size from largest  (sharks) to smallest (Calamus  spp.). The mean size of each  group within time period is  indicated with shading.

Species composition of displayed trophy fish in 1956–1960, 1965–1979, 1980–1985, and 2007 arranged in order of size from largest (sharks) to smallest (Calamus spp.). The mean size of each group within time period is indicated with shading.

Tagged with:
 

3 Responses to Where have all the big fish gone? Part II: A case study from the Florida Keys

  1. John Bruno says:

    This paper has also highlighted the shortcomings of a “historical ecology” approach, particularly one performed in a vacuum in libraries. The really big goliath grouper seen in the earliest photos, are in fact thriving in the Fl Keys due to very successful fisheries management and MPAs. The reason they are no longer on the fishing docks is because it is illegal to catch them! Not because they are gone. They are now on the reefs where they should be. That isn’t to say there were not more of them back in the day. But they are certainly not extinct, as this research implies.

  2. J.Roff says:

    Hi John,

    I don’t see this as a shortcoming at all – clearly the paper doesn’t suggest that goliath grouper is extinct, especially since the moratorium on grouper fishing in the 90′s is actually highlighted and discussed in the paper:

    “Declines in the size of Epinephelus groupers caught and displayed were detected in 2007 owing to restrictions on harvest of 2 of the largest species targeted, goliath (E. itajara) and Nassau (E. striatus) groupers. A moratorium on these species was enacted in 1990 and 1997, respectively (Reef Fish Fishery Management Plan 2008 [Gulf of Mexico Fishery Management Council 2008]). Therefore, declines detected in Epinephelus groupers did not represent actual declines in the size of fish

    I’ve posted another image from the paper after the jump that shows the proportion of individuals in each time period, again showing considerable shifts in species composition and size classes of fish over the past half century.

    In a follow-up paper in the journal Endangered Species Research on goliath grouper trends prior to the fisheries closure in the 1990′s, analysis of historical photographs shows fairly convincingly that the average number of individuals per trip decreased before 1960, and was reduced by 86% before 1979. Furthermore, historical records of grouper landings (1922 – 1977) show decreases in the maximum size and proportion of grouper caught on land vs offshore prior to 1950.

    To dismiss historical studies as being ‘performed in a vacuum of libraries’ is offhand and missing the point entirely. Indeed, fisheries management in the absence of historical context is somewhat akin to managing in a vacuum. In the case of the the goliath grouper, the NMFS seems to be doing a great job of managing against historical estimates, and that whilst no longer in immediate danger of extinction, the species cannot be considered as fully recovered (let alone ‘thriving’) until fisheries biomass matches historical estimates (see here for a great discussion using historical data).

  3. Doug Hepler says:

    We are planning to construct, place and use a shallow-water observation habitat here on Kwajalein. I have been working on the design proposal for almost 7 years now. It will be supplied from a shore air compressor, and will be in 15 FSW, “manned” by high school Marine Science students (most of whom are SCUBA divers). Even though we are a restricted military base, with no real pollution/overfishing issues, we nonetheless see the increasing effects of climate change, even “way out here”.

    If there are any tips you have to share, with regard to specific observations/observaion procedures our kids might use when utilizing this habitat, please let me know.

    All the best,
    Doug Hepler
    Teacher, Kwajalein Jr-Sr High School
    NAUI OWSI #32120

Leave a Reply

Your email address will not be published. Required fields are marked *


*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Set your Twitter account name in your settings to use the TwitterBar Section.