[MARMAM] New publication: A machine-learning approach to assign species to ‘unidentified’ entangled whales.

Jim Carretta - NOAA Federal jim.carretta at noaa.gov
Mon Jul 2 12:03:55 PDT 2018

Dear Colleagues,

I am pleased to share a new publication from Endangered Species Research:

Carretta, J.V. 2018. A machine-learning approach to assign species to
‘unidentified’ entangled whales.


ABSTRACT: Whale entanglements in US west coast fishing gear are largely
represented by
opportunistic sightings, and some reports lack species identifications due
to rough seas, distance
from whales, or a lack of cetacean identification expertise. Unidentified
entanglements are often
ignored in species risk assessments and thus, entanglement risk is
underestimated. To address
this negative bias, a species identification model was built from random
forest (RF) classification
trees using 199 identified entanglements (‘model data’). Humpback Megaptera
novaeangliae and
gray whales Eschrichtius robustus represented 92% of identified
entanglements; the remaining
8% were minke whales Balaenoptera acutorostrata, fin whales B. physalus,
blue whales B. musculus,
and sperm whales Physeter macrocephalus. Predictor variables included year,
gear type,
location, season, sea surface temperature, water depth, and a multivariate
El Niño index. Cross validated
species classifications were correct in 78% (155/199) of cases,
significantly higher
(p < 0.001, permutation test) than the 49% correct classification rate
expected by chance. The RF
model correctly classified 91% of humpback whale cases, 64% of gray whale
cases, and 100% of
sperm whale cases, but misclassified all minke, blue, and fin whale cases.
The cross-validated RF
classification-tree species model was used to classify 35 entanglements
without species identifications
(‘novel data’) and each case was assigned a probability of belonging to
each of 6 model data
species. This approach eliminates the negative bias associated with
ignoring unidentified entanglements
in species risk assessments. Applications to other wildlife studies where
some detections
are unidentified include fisheries bycatch, line-transect surveys, and
large-whale vessel strikes.

The article is open-access and a direct link to the article is here:

Sincerely, Jim Carretta
jim.carretta at noaa.gov
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