Unlikely the biodiversity crisis will improve any time soon

6 02 2020

hopelessAround a fortnight ago I wrote a hastily penned post about the precarious state of biodiversity — it turned out to be one of the most-read posts in ConservationBytes‘ history (nearly 22,000 views in less than two weeks).

Now, let’s examine whether this dreadful history is likely to get any better any time soon.

Even if extinction rates decline substantially over the next century, I argue that we are committed to an intensifying biodiversity extinction crisis. The aggregate footprint from the growing human population notwithstanding, we can expect decades, if not centuries, of continued extinctions from lag effects alone (extinction debts arising from previous environmental damage engendering extinctions in the future)1.

Global vegetation cover and production are also likely to decline even in the absence of continued habitat clearing — the potential benefit of higher CO2 concentrations for plant photosynthesis is more than offset by lower availability of water in the soil, heat stress, and the frequency of disturbances such as droughts2. Higher frequencies and intensities of disturbance events like catastrophic bushfire will also exacerbate extinction rates3.

However, perhaps the least-appreciated element of potential extinctions arising from climate change is that they are vastly underestimated when only considering a species’ thermal tolerance4. In fact, climate disruption-driven extinction rates could be up to ten times higher than currently predicted4 when extinction cascades are taken into account5. Read the rest of this entry »





Sustainable kangaroo harvests

10 11 2011

When I first started this blog back in 2008, I extolled the conservation virtues of eating kangaroos over cattle and sheep. Now I want to put my academic money where my mouth is, and do some kangaroo harvest research.

Thanks to the South Australia Department of Environment and Natural Resources  (DENR) and the commercial kangaroo harvest industry, in conjunction with the University of Adelaide, I’m pleased to announce a new scholarship for a PhD candidate to work on a project entitled Optimal survey and harvest models for South Australian macropods based at the University of Adelaide’s School of Earth and Environmental Sciences.

DENR is custodian of a long-term macropod database derived from the State’s management of the commercial kangaroo harvest industry. The dataset entails aerial survey data for most of the State from 1978 to present, annual population estimates, quotas and harvests for three species: red kangaroo (Macropus rufus), western grey kangaroo (Macropus fuliginosus), and the euro (Macropus robustus erubescens). Read the rest of this entry »





Oceans need their giants

2 11 2011

Another great post from Salvador Herrando Pérez.

from adsown.blogspot.com

Commercial and sport fishing establish minimum body sizes for catches of many species to preserve fish stocks. Recent work reveals that sustainable fisheries also depend on the regulation of the harvest of the biggest fish, at least in long-lived species.

Growing up in Spain in the 1980s, I was taken by a Spanish television spot featuring a shoal of little fish sucking colourful dummies, and at the same time (how they managed, I never questioned) singing the motto Little fish? No, thanks. The then Ministry of Agriculture, Fishery and Food created this media campaign to create awareness among consumers not to buy immature fish at local markets – “…a 60-gram hake will only weigh 2 kg after two years” the add stated.

Indeed, the regulation of fish harvest by age classes is substantial to any fishery. In particular, the protection of younger fish has been a beacon of fishery policy and management that dates back to the 19th century when, among others, the British ichthyologist Ernst Holt concluded that: “…it is desirable that fish should have a chance of reproducing their species at least once before they are destroyed” 1. Very much in line with such principles, conventional fish stock management has in practice neglected the mature age classes2, other than for the fact that they are the end point of extraction and what we consumers eat on the table. Read the rest of this entry »