When you are tal­king about the “slow reco­very of wha­le popu­la­ti­on after indus­tri­al wha­ling”, then the empha­sise is on “slow” rather than on “reco­very”, depen­ding on the spe­ci­es. All lar­ge baleen wha­le spe­ci­es whe­re hun­ted inten­si­ve­ly with indus­tri­al­ly bru­tal methods in the sou­thern hemi­sphe­re, most­ly bet­ween 1890 and 1970, alt­hough wha­ling (main­ly by Japa­ne­se wha­lers) is still an ongo­ing fact, as most rea­ders will be awa­re of. Natu­ral, pre-wha­ling popu­la­ti­ons were redu­ced to frac­tions. The actu­al size of the ori­gi­nal popu­la­ti­ons can only be esti­ma­ted.

With today’s know­ledge of repro­duc­tion, food resour­ces etc., pre­dic­tions of the future deve­lo­p­ment of wha­le popu­la­ti­ons can be made. Of cour­se, the­re are uncer­tain­ties inher­ent as with any model-based (or other) pre­dic­tion, but some trends are nevert­hel­ess quite clear.

Results vary, depen­ding on the spe­ci­es, as a recent stu­dy by Aus­tra­li­an bio­lo­gists shows. Hump­back wha­les may be back to a natu­ral popu­la­ti­on level, esti­ma­ted near 100,000 indi­vi­du­als, as “soon” as around 2050. Curr­ent­ly, the­re is only a third of that num­ber around, but hump­back wha­le cows may give birth to a calf every year and they are bene­fit­ting from a solid nut­ri­ti­on base.

The lar­ger spe­ci­es such as fin, blue and sou­thern right wha­les will take more time. Their fema­les five birth only once in 2-3 years. Reco­very is accor­din­gly much slower, and popu­la­ti­on levels may not be more than half of the ori­gi­nal size in 2100, more than 100 years after wha­ling most­ly came to an end. Fac­tors like cli­ma­te chan­ge and its influen­ces on the mari­ne food web and the poten­ti­al thre­at of more wha­ling in the future bring addi­tio­nal uncer­tain­ty.

Source: csirau.au