Genomics will not be harmed despite intense whaling

Fin whales are the sec­ond largest crea­tures on our plan­et, sur­passed only by blue whales. They can reach a length of around 20 meters — and require up to two tons of food per day. Accord­ing­ly, they release enor­mous amounts of nutri­ents — with sig­nif­i­cant effects on ocean ecosys­tems. Indus­tri­al whal­ing, how­ev­er, has sig­nif­i­cant­ly reduced their num­bers. It was aimed at the tran of whales as raw mate­r­i­al and was par­tic­u­lar­ly inten­sive between 1880 and an inter­na­tion­al agree­ment in 1986. Today, the num­ber of fin whales world­wide is esti­mat­ed at about 100,000 ani­mals; the species is con­sid­ered endan­gered accord­ing to the Red List. A new study by sci­en­tists from the LOEWE Cen­ter for Trans­la­tion­al Bio­di­ver­si­ty Genomics (TBG), the Senck­en­berg Bio­di­ver­si­ty and Cli­mate Research Cen­ter (SBiK‑F), and Ice­landic and Swedish research insti­tu­tions shows the con­se­quences of their dec­i­ma­tion for the pop­u­la­tions and espe­cial­ly for the genom­ic diver­si­ty of fin whales. For­tu­nate­ly, their results show no long-term genet­ic weak­en­ing of this species.

After fin whales were hunt­ed in the ear­ly 20th cen­tu­ry until local whal­ing indus­tries col­lapsed in some places due to declin­ing catch­es — such as in the waters around Nor­we­gian Finn­mark in 1904 — there were fears of glar­ing con­se­quences, includ­ing extinc­tion of the species due to inbreed­ing. For the study pub­lished in the jour­nal “Mol­e­c­u­lar Biol­o­gy and Evo­lu­tion”, the sci­en­tists now exam­ined 51 genomes of a North Atlantic fin whale pop­u­la­tion from Ice­landic waters for the first time. Using the sam­ples from 1989, 2009 and 2018, they devel­oped demo­graph­ic mod­els that allow con­clu­sions to be drawn about pop­u­la­tion changes over around 800 years. The analy­ses focused on whether whal­ing also affect­ed the genet­ic diver­si­ty of fin whales.

The team con­cludes that whal­ing had a strong impact on pop­u­la­tions in the North Atlantic, dec­i­mat­ing them to as much as twen­ty per­cent of their pre­vi­ous size with­in about one hun­dred years. How­ev­er, the team also showed that dif­fer­ent pop­u­la­tions were hit dif­fer­ent­ly by whal­ing, as the genomes of some ani­mals showed lit­tle or no trace of this pop­u­la­tion reduction.

“Look­ing at the genet­ic diver­si­ty of a species allows us to draw con­clu­sions about whether and how well that species can adapt to new envi­ron­men­tal con­di­tions or changes in its pop­u­la­tion, or whether it is like­ly to go extinct. There­fore, genom­ic analy­sis can often reveal trends before they become overt. How­ev­er, in the case of North Atlantic fin whales, we did not detect a sig­nif­i­cant loss of their diver­si­ty in the long-term perspective.”

- Mag­nus Wolf, lead author of the study

Oth­er genet­ic con­se­quences with­in the deplet­ed fin whale stocks also appear to have failed to mate­ri­al­ize. Nei­ther did the sci­en­tists* find evi­dence of fre­quent inbreed­ing, where genomes become unnat­u­ral­ly sim­i­lar, nor could a greater num­ber of genet­ic defects be detect­ed that would bur­den the pop­u­la­tion in the long term. “Such muta­tions occur all the time, but they are more notice­able in small pop­u­la­tions because some­times there are then no ani­mals with­out the muta­tion left to pre­vail,” Wolf said.

So, com­pared to more endan­gered cetacean species such as the blue whale or North Atlantic right whale, cur­rent human impacts seem to be the main obsta­cle to fin whale recov­ery. These include increas­ing ship­ping traf­fic and pol­lu­tion of the seas. The Inter­na­tion­al Union for Con­ser­va­tion of Nature (IUCN) has clas­si­fied fin whales as an endan­gered species on its Red List. There­fore, there is cur­rent­ly no all-clear for their sit­u­a­tion, empha­sizes Prof. Dr. Axel Janke, lead sci­en­tist of the study, sci­en­tif­ic coor­di­na­tor and spokesper­son of the LOEWE Cen­ter TBG and also work­ing at SBiK‑F and the Insti­tute for Ecol­o­gy, Evo­lu­tion and Diver­si­ty at Goethe Uni­ver­si­ty Frankfurt.

“It is fas­ci­nat­ing how genom­ic insights can con­tribute to our pic­ture of whale con­ser­va­tion. Genomics is emerg­ing as a key tech­nol­o­gy not only for species con­ser­va­tion, but also helps us under­stand what bio­di­ver­si­ty actu­al­ly is and how we can use it. Whales are not only impres­sive ani­mals, but despite their long lifes­pan of up to one hun­dred years and their body size, they also seem to devel­op hard­ly any tumors and are thus resis­tant to can­cer. Deci­pher­ing the genom­ic mech­a­nisms that cause this para­dox could help us address one of the most con­se­quen­tial dis­eases in human history.”