Newborn harbour porpoises have the fastest hearing development among mammals

Date: March 2, 2017

Source: University of Southern Denmark

All mammals can hear -- but it is not an ability that is fully developed at birth. Some mammals like humans take years to fully develop their hearing abilities, but for a newborn harbor porpoise it takes less than 30 hours. This is the fastest in any studied mammal.

It takes less than 30 hours for a newborn harbor porpoise (Phocoena phocoena) to develop full hearing abilities. This is faster than any other mammals studied.

Hearing is the most important of the senses for a porpoise, both for adults and calves, so it is logical that a newborn calf spends energy on fine tuning and optimizing this sense as fast as possible, says biologist Magnus Wahlberg, University of Southern Denmark.

Together with colleagues Lara Delgado-García from SDU and Jakob Højer Kristensen from the research and experience center Fjord&Bælt in Kerteminde, Denmark, he has published a study in Journal of Comparative Physiology A.

Rabbits need months to develop full hearing

Mammals are not born with fully developed hearing. It may take weeks, months or years, and land living mammals need the most time. Guinea pigs need weeks. Cats, rabbits, minks, bats and rats need months. And humans may need years.

A newborn porpoise calf needs a good hearing, so that it can maintain contact with its mother and develop echolocation skills, says Jakob Højer Kristensen.

Continued https://www.sciencedaily.com/releases/2017/03/170302115734.htm

Harbour porpoises are skilled hunters and eat almost constantly

Date: May 26, 2016

Source: Cell Press

Harbour porpoises have sometimes been described as "living in the fast lane." Being smaller than other cetaceans and living in cold northern waters means that the porpoises require a lot of energy to survive, making them prone to starvation. Now researchers reporting in the Cell Press journal Current Biology on May 26 have monitored harbour porpoises in the wild with tiny computers attached to them by suction cups show that the animals hunt and eat almost constantly.

The findings by researchers in Denmark, Germany, and Scotland suggest that even a moderate level of disturbance in the busy shallow waters that they share with humans--anything that might limit their ability to feed--could put the animals in serious jeopardy.

"Our results show that porpoises hunt small fish, typically less than five centimeters, nearly continuously day and night at ultra-high rates, attempting to capture up to 550 fish per hour, and frequently more than ten per minute with a remarkable success rate of more than 90 percent," says Danuta Wisniewska of Aarhus University in Denmark. "The tiny fish targeted by porpoises are not of interest in commercial fisheries; however, relying on such small prey makes porpoises especially vulnerable to disturbances, because there is no room for compensation."

To study the animals' foraging behaviors, the researchers attached miniature computers developed at University of St. Andrews to five wild porpoises. The computers recorded the porpoises' echolocation calls and the echoes that came back as those calls bounced off of nearby prey. By analyzing the sound, the researchers were able to determine how often porpoises attempted to catch fish. They could also estimate the size of those fish and whether the fish managed to escape.

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Whale research vessel begins porpoise survey in the Thames Estuary

The survey hopes to get an accurate picture of Harbour Porpoises in the Thames Estuary

A research team on board the unique, non-invasive whale research vessel Song of the Whale will carry out the first ever comprehensive scientific study to assess the population of Harbour Porpoises (the UK’s smallest cetacean) in the Thames Estuary between March 5 and 14.

In all, the survey will cover the area from Ipswich, travelling up the Thames through central London to Tower Bridge, the Thames Barrier, Teddington Lock and the Outer Estuary.

Marine Conservation Research International (MCR), which owns and operates the boat, will carry out acoustic and visual surveys using underwater microphones (hydrophones) and visual techniques, funded by the International Fund for Animal Welfare (IFAW) and with help from conservationists from the Zoological Society of London (ZSL).

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Grey seals found to prey on porpoises

As well as fish suppers grey seals are also partial to a Harbour Porpoise dinner, according to new research.

Hundreds of mutated porpoises have been washing up on Dutch beaches over the last decade with no hint of a cause. 

Back in 2012 Belgian researchers suggested that grey seals might be preying on porpoises. A year later a French research group published images of a swimming porpoise appearing to be under attack from a grey seal. However until now there has been no evidence the seals were actually killing the porpoises.

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