La buona notizia: la megattera non è più in pericolo di estinzione

di Marco Mancini 31

megattera

La US National Marine Fisheries Service può rimuovere la megattera, o Balena gobba, dal suo elenco delle specie minacciate di estinzione, citando la prova che gli esemplari, che fino a poco tempo fa erano quasi estinti, sono aumentati di numero. Poiché un divieto internazionale della caccia alle balene fu imposto nel 1966, le popolazioni di megattere del Pacifico settentrionale sono aumentate di circa il 4,7% ogni anno, dicono i ricercatori.

La gran parte della causa del rischio di estinzione era la tendenza a frequentare le acque costiere, che le portava ad essere catturate dai balenieri commerciali in tutto il mondo. La Balena gobba veniva cacciata per il suo olio, carne e ossa. La maggior parte della popolazione è stata drasticamente ridotta nella prima parte del 19° secolo, lasciando solo tra il 5 e il 10% del numero di esemplari ereditati dall’800. Nel Pacifico settentrionale, si stima che ben 15.000 megattere esistevano prima del 1900, meno di un migliaio sono arrivate a superare la metà del secolo.

La popolazione è stata decimata prima del divieto internazionale alla caccia commerciale istituito nel 1964. Oggi, la popolazione del Nord Pacifico, che ritorna alle Hawaii nei mesi invernali, è attualmente composta da circa 2.000 esemplari. A dispetto dei loro recenti passi verso il ripopolamento, le balene continuano ad essere designate come una specie minacciata. Solo un’altra specie, la balena fanone, è considerata più a rischio rispetto alle megattere.

Un’altra attività umana che pone una seria minaccia è la pesca a strascico. Enormi reti in nylon leggero che misurano tra fino a 140 km di lunghezza e tra i 2 e i 5 metri di profondità sono lasciate alla “deriva” in mare aperto per un periodo di 8 ore o più, e sono in grado di prendere di tutto, dai pesci “leciti” agli animali in via d’estinzione.

La maggior parte degli animali che rimangono impigliati in queste reti non sono in grado di liberarsi e annegano. Migliaia di balene, delfini, uccelli marini e tartarughe muoiono inutilmente ogni anno in questo modo. Grazie al divieto, si stima che tra le 18.000 e le 20.000 megattere oggi esistono nel nord del Pacifico, un forte aumento dal 1960, quando le popolazioni erano scese a circa 1.400. Circa 60.000 esemplari esistono in tutto il mondo, secondo l’Unione Internazionale per la Conservazione della Natura.

Ma questo non deve far credere che siccome la popolazione è aumentata, si può riprendere a cacciarle. Non sono più in pericolo di estinzione, ma se si riaprisse la caccia alle balene, il rischio di ritornare nell’abisso sarebbe altissimo.

Fonte: [Enn]

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