Species on The Brink & SIO 296 Wrap Up. Phaedra Doukakis Sarah Mesnick. Vaquita. Sturgeon. New concepts, common themes. Abalone. Baiji. Where are we in the spectrum of decline?. Stages of decline: Pre-exploitation (“natural”) Exploited Overfished Commercially extinct
New concepts, common themes
Murphy 1966 and Hill et al. 2009
Often, we begin to act too late and do too little…
Compared to decline, we know relatively little about recovery
Inbreeding depression (no threat (yet)…many calves, naturally rare)
Lack of Colorado River flow (no threat now)
Dead vaquita fat
Many fewer vaquita than normal levels
Bycatch (accidental death in fishing nets)
Estimated 78/year…is that too many?
but not so happy
Looking closely at the effects of some threats and at mitigation options
Life-history Important mitigation options
Late maturity, infrequent reproduction
Caspian Sea 1966
3 mitigation options
Vaquita: Tiny distribution;
Described as a new species
In 1958 (Norris & McFarland)
From Hobday et al. 2001
Value & Rarity Effect, Sex Ratios
$8,000/kilo for black caviar
$115.00/lb for abalone
Guinness World Record Most Valuable Fish: Russian sturgeon 2,706 lb caught in 1924: 540 lb of caviar, today worth nearly $1.35-2.7 million.
Tools: Using genetics to regulate trade and markets Effect, Sex Ratios
Eggs look like eggs; high potential for fraud.
Genetics & Restoration Effect, Sex Ratios
Genetics: DISEASE RESISTANCE? Effect, Sex RatiosWild Black Abalone +/- WS
Tools: AQUACULUTRE AS A REPLACEMENT FOR WILD Effect, Sex Ratios
World Abalone Production (FA0)
Total Production Effect, Sex Ratios
Can we distinguish wild from farmed?
Tools: Estimating Abundance: Acoustics Effect, Sex Ratios
ROV Operations: abundance & habitat estimates Effect, Sex Ratios
Green sturgeon: Effect, Sex Ratios
Habitat use and characteristics
1. Natural population fluctuations in abundance, recruitment and geographic range can contribute to natural variations in extinction risk below critical points in population structure.
2. Variations in extinction risk affect the potential for extinction from natural causes (which could be stochastic) and can be exacerbated by human activities whether these directly target the species or not (Vaquita).
3. The slow pace by which humans recognize threats to species and the lags in political systems mean that valuable species or those with large natural fluctuations in abundance are particularly threatened.
4. Climate change adds a particularly damaging aspect to threats to species since future changes are expected to: (a) increase natural variability, and (b) have considerable built in momentum that will make it difficult to reduce a threat once it appears (like acidification).
5. Little or no money to monitor or regulate international trade in species for which there is no commercial take (other than ESA).