Assessment of the size distribution of the big-scale sand smelt (Atherina boyeri Risso, 1810) in the diet of the Caspian seal (Pusa caspica Gmellin, 1788) using fish otoliths from fecal samples

利用粪便样本中的鱼耳石评估里海海豹（Pusa caspica Gmellin, 1788）食物中大型沙丁鱼（Atherina boyeri Risso, 1810）的体型分布